diff --git a/CanonSharp.Pascal/Parser/GrammarParser.cs b/CanonSharp.Pascal/Parser/GrammarParser.cs
index 2ce60b2..78bd12e 100644
--- a/CanonSharp.Pascal/Parser/GrammarParser.cs
+++ b/CanonSharp.Pascal/Parser/GrammarParser.cs
@@ -32,6 +32,13 @@ public sealed class GrammarParser : GrammarParserBuilder
             from _2 in Delimiter(")")
             select node;
 
+        IParser<LexicalToken, SyntaxNodeBase> procedureCallParser =
+            from identifier in IdentifierParser()
+            from _ in Delimiter("(")
+            from expressions in ExpressionParser().SeparatedBy(Delimiter(","))
+            from _1 in Delimiter(")")
+            select new ProcedureCallNode(identifier, expressions);
+
         return Choice(
             TrueParser(),
             FalseParser(),
@@ -39,6 +46,7 @@ public sealed class GrammarParser : GrammarParserBuilder
             minusParser,
             plusParser,
             notParser,
+            procedureCallParser,
             VariableParser(),
             parenthesisParser
         );
@@ -189,6 +197,19 @@ public sealed class GrammarParser : GrammarParserBuilder
             select new WhileNode(condition, statement);
     }
 
+    public static IParser<LexicalToken, ProcedureCallNode> ProcedureCallParser()
+    {
+        return Choice(
+            from identifier in IdentifierParser()
+            from _ in Delimiter("(")
+            from expressions in ExpressionParser().SeparatedBy(Delimiter(","))
+            from _1 in Delimiter(")")
+            select new ProcedureCallNode(identifier, expressions),
+            from identifier in IdentifierParser()
+            select new ProcedureCallNode(identifier, [])
+        );
+    }
+
     public static IParser<LexicalToken, SyntaxNodeBase> StatementParser()
     {
         return Choice<LexicalToken, SyntaxNodeBase>(
@@ -196,6 +217,7 @@ public sealed class GrammarParser : GrammarParserBuilder
             from _ in Operator(":=")
             from expression in ExpressionParser()
             select new AssignNode(variable, expression),
+            ProcedureCallParser(),
             IfParser(),
             ForParser(),
             WhileParser(),
@@ -236,7 +258,7 @@ public sealed class GrammarParser : GrammarParserBuilder
             select new ConstantNode(identifier, node);
     }
 
-    public static IParser<LexicalToken, SyntaxNodeBase> ConstDeclarationsParser()
+    public static IParser<LexicalToken, BlockNode> ConstDeclarationsParser()
     {
         return (from _ in Keyword("const")
             from tokens in ConstDeclarationParser().SeparatedOrEndBy1(Delimiter(";"))
@@ -283,12 +305,73 @@ public sealed class GrammarParser : GrammarParserBuilder
             select new BlockNode(nodes)).Try(new BlockNode([]));
     }
 
-    public static IParser<LexicalToken, ProgramBody> ProgramBodyParser()
+    public static IParser<LexicalToken, IEnumerable<Parameter>> ParameterParser()
+    {
+        return Choice(
+            from _ in Keyword("var")
+            from tokens in IdentifierParser().SeparatedBy1(Delimiter(","))
+            from _1 in Delimiter(":")
+            from typeToken in TypeParser()
+            select tokens.Select(x => new Parameter(true, x, typeToken)),
+            from tokens in IdentifierParser().SeparatedBy1(Delimiter(","))
+            from _ in Delimiter(":")
+            from typeToken in TypeParser()
+            select tokens.Select(x => new Parameter(false, x, typeToken))
+        );
+    }
+
+    public static IParser<LexicalToken, IEnumerable<Parameter>> FormalParameterParser()
+    {
+        return (from _ in Delimiter("(")
+            from parameters in ParameterParser().SeparatedBy(Delimiter(";"))
+            from _1 in Delimiter(")")
+            select parameters.Aggregate(new List<Parameter>(), (result, array) =>
+            {
+                result.AddRange(array);
+                return result;
+            })).Try([]);
+    }
+
+    public static IParser<LexicalToken, SubprogramHead> SubprogramHeadParser()
+    {
+        return Choice(
+            from _ in Keyword("procedure")
+            from identifier in IdentifierParser()
+            from parameters in FormalParameterParser()
+            select new SubprogramHead(identifier, parameters),
+            from _ in Keyword("function")
+            from identifier in IdentifierParser()
+            from parameters in FormalParameterParser()
+            from _1 in Delimiter(":")
+            from typeToken in TypeParser()
+            select new SubprogramHead(identifier, parameters, typeToken)
+        );
+    }
+
+    public static IParser<LexicalToken, SubprogramBody> SubprogramBodyParser()
     {
         return from constant in ConstDeclarationsParser()
             from variables in VariableDeclarationsParser()
             from block in CompoundStatementParser()
-            select new ProgramBody(constant.Convert<BlockNode>(), variables, block);
+            select new SubprogramBody(constant, variables, block);
+    }
+
+    public static IParser<LexicalToken, Subprogram> SubprogramParser()
+    {
+        return from head in SubprogramHeadParser()
+            from _ in Delimiter(";")
+            from body in SubprogramBodyParser()
+            select new Subprogram(head, body);
+    }
+
+    public static IParser<LexicalToken, ProgramBody> ProgramBodyParser()
+    {
+        return from constant in ConstDeclarationsParser()
+            from variables in VariableDeclarationsParser()
+            from subprograms in SubprogramParser().SeparatedOrEndBy(Delimiter(";"))
+                .Map(x => new BlockNode(x))
+            from block in CompoundStatementParser()
+            select new ProgramBody(constant, variables, subprograms, block);
     }
 
     public static IParser<LexicalToken, ProgramHead> ProgramHeadParser()
diff --git a/CanonSharp.Pascal/SyntaxTree/Parameter.cs b/CanonSharp.Pascal/SyntaxTree/Parameter.cs
new file mode 100644
index 0000000..3674f29
--- /dev/null
+++ b/CanonSharp.Pascal/SyntaxTree/Parameter.cs
@@ -0,0 +1,14 @@
+using CanonSharp.Pascal.Scanner;
+
+namespace CanonSharp.Pascal.SyntaxTree;
+
+public sealed class Parameter(bool isReference, LexicalToken identifier, SyntaxNodeBase typeNode) : SyntaxNodeBase
+{
+    public override SyntaxNodeType NodeType => SyntaxNodeType.Parameter;
+
+    public bool IsReference => isReference;
+
+    public LexicalToken Identifier => identifier;
+
+    public SyntaxNodeBase TypeNode => typeNode;
+}
diff --git a/CanonSharp.Pascal/SyntaxTree/ProcedureCallNode.cs b/CanonSharp.Pascal/SyntaxTree/ProcedureCallNode.cs
new file mode 100644
index 0000000..9824e3e
--- /dev/null
+++ b/CanonSharp.Pascal/SyntaxTree/ProcedureCallNode.cs
@@ -0,0 +1,18 @@
+using CanonSharp.Pascal.Scanner;
+
+namespace CanonSharp.Pascal.SyntaxTree;
+
+public sealed class ProcedureCallNode : SyntaxNodeBase
+{
+    public ProcedureCallNode(LexicalToken identifier, IEnumerable<SyntaxNodeBase> parameters)
+    {
+        Identifier = identifier;
+        Parameters.AddRange(parameters);
+    }
+
+    public override SyntaxNodeType NodeType => SyntaxNodeType.ProcedureCall;
+
+    public LexicalToken Identifier { get; }
+
+    public List<SyntaxNodeBase> Parameters { get; } = [];
+}
diff --git a/CanonSharp.Pascal/SyntaxTree/ProgramBody.cs b/CanonSharp.Pascal/SyntaxTree/ProgramBody.cs
index df88d62..cb42698 100644
--- a/CanonSharp.Pascal/SyntaxTree/ProgramBody.cs
+++ b/CanonSharp.Pascal/SyntaxTree/ProgramBody.cs
@@ -1,6 +1,9 @@
 namespace CanonSharp.Pascal.SyntaxTree;
 
-public sealed class ProgramBody(BlockNode constantDeclarations, BlockNode variableDeclarations, BlockNode mainBlock) : SyntaxNodeBase
+public sealed class ProgramBody(BlockNode constantDeclarations, BlockNode variableDeclarations,
+    BlockNode subprograms,
+    BlockNode mainBlock)
+    : SyntaxNodeBase
 {
     public override SyntaxNodeType NodeType => SyntaxNodeType.ProgramBody;
 
@@ -8,5 +11,7 @@ public sealed class ProgramBody(BlockNode constantDeclarations, BlockNode variab
 
     public BlockNode VariableDeclarations => variableDeclarations;
 
+    public BlockNode Subprograms => subprograms;
+
     public BlockNode MainBlock => mainBlock;
 }
diff --git a/CanonSharp.Pascal/SyntaxTree/Subprogram.cs b/CanonSharp.Pascal/SyntaxTree/Subprogram.cs
new file mode 100644
index 0000000..97b5cdc
--- /dev/null
+++ b/CanonSharp.Pascal/SyntaxTree/Subprogram.cs
@@ -0,0 +1,10 @@
+namespace CanonSharp.Pascal.SyntaxTree;
+
+public sealed class Subprogram(SubprogramHead subprogramHead, SubprogramBody subprogramBody) : SyntaxNodeBase
+{
+    public override SyntaxNodeType NodeType => SyntaxNodeType.SubProgram;
+
+    public SubprogramHead Head => subprogramHead;
+
+    public SubprogramBody Body => subprogramBody;
+}
diff --git a/CanonSharp.Pascal/SyntaxTree/SubprogramBody.cs b/CanonSharp.Pascal/SyntaxTree/SubprogramBody.cs
new file mode 100644
index 0000000..f580864
--- /dev/null
+++ b/CanonSharp.Pascal/SyntaxTree/SubprogramBody.cs
@@ -0,0 +1,12 @@
+namespace CanonSharp.Pascal.SyntaxTree;
+
+public sealed class SubprogramBody(BlockNode constDeclarations, BlockNode variableDeclarations, BlockNode mainBlock) : SyntaxNodeBase
+{
+    public override SyntaxNodeType NodeType => SyntaxNodeType.SubprogramBody;
+
+    public BlockNode ConstDeclarations => constDeclarations;
+
+    public BlockNode VariableDeclarations => variableDeclarations;
+
+    public BlockNode MainBlock => mainBlock;
+}
diff --git a/CanonSharp.Pascal/SyntaxTree/SubprogramHead.cs b/CanonSharp.Pascal/SyntaxTree/SubprogramHead.cs
new file mode 100644
index 0000000..27d50bb
--- /dev/null
+++ b/CanonSharp.Pascal/SyntaxTree/SubprogramHead.cs
@@ -0,0 +1,28 @@
+using CanonSharp.Pascal.Scanner;
+
+namespace CanonSharp.Pascal.SyntaxTree;
+
+public sealed class SubprogramHead : SyntaxNodeBase
+{
+    public override SyntaxNodeType NodeType => SyntaxNodeType.SubprogramHead;
+
+    public LexicalToken Identifier { get; }
+
+    public List<Parameter> Parameters { get; } = [];
+
+    public SyntaxNodeBase? TypeToken { get; }
+
+    public SubprogramHead(LexicalToken identifier, IEnumerable<Parameter> parameters)
+    {
+        Identifier = identifier;
+        Parameters.AddRange(parameters);
+        TypeToken = null;
+    }
+
+    public SubprogramHead(LexicalToken identifier, IEnumerable<Parameter> parameters, SyntaxNodeBase typeToken) : this(
+        identifier, parameters)
+    {
+        TypeToken = typeToken;
+    }
+
+}
diff --git a/CanonSharp.Pascal/SyntaxTree/SyntaxNodeBase.cs b/CanonSharp.Pascal/SyntaxTree/SyntaxNodeBase.cs
index 31e412d..d57266e 100644
--- a/CanonSharp.Pascal/SyntaxTree/SyntaxNodeBase.cs
+++ b/CanonSharp.Pascal/SyntaxTree/SyntaxNodeBase.cs
@@ -17,6 +17,11 @@ public enum SyntaxNodeType
     If,
     While,
     For,
+    ProcedureCall,
+    Parameter,
+    SubprogramHead,
+    SubprogramBody,
+    SubProgram,
     ProgramBody,
     ProgramHead,
     Program
diff --git a/CanonSharp.Tests/ParserTests/ExpressionParserTests.cs b/CanonSharp.Tests/ParserTests/ExpressionParserTests.cs
index 5961a1d..16af0a3 100644
--- a/CanonSharp.Tests/ParserTests/ExpressionParserTests.cs
+++ b/CanonSharp.Tests/ParserTests/ExpressionParserTests.cs
@@ -82,6 +82,23 @@ public sealed class ExpressionParserTests : GrammarParserTestBase
         Assert.Equal(1, binaryOperatorNode.Right.Convert<IntegerValueNode>().Value);
     }
 
+    [Fact]
+    public void ProcedureCallTest()
+    {
+        ProcedureCallNode node = RunParser<ProcedureCallNode>(GrammarParser.FactorParser(), "test(1)");
+        Assert.Equal("test", node.Identifier.LiteralValue);
+        Assert.Single(node.Parameters);
+        Assert.Equal(1, node.Parameters[0].Convert<IntegerValueNode>().Value);
+
+        node = RunParser<ProcedureCallNode>(GrammarParser.FactorParser(), "test()");
+        Assert.Equal("test", node.Identifier.LiteralValue);
+        Assert.Empty(node.Parameters);
+
+        VariableNode variableNode = RunParser<VariableNode>(GrammarParser.FactorParser(), "test");
+        Assert.Equal("test", variableNode.Identifier.LiteralValue);
+        Assert.Empty(variableNode.Indexers);
+    }
+
     [Fact]
     public void SingleTermTest()
     {
diff --git a/CanonSharp.Tests/ParserTests/ProgramParserTests.cs b/CanonSharp.Tests/ParserTests/ProgramParserTests.cs
index 03d21c5..1dad715 100644
--- a/CanonSharp.Tests/ParserTests/ProgramParserTests.cs
+++ b/CanonSharp.Tests/ParserTests/ProgramParserTests.cs
@@ -153,6 +153,75 @@ public class ProgramParserTests : GrammarParserTestBase
                 i := i + 1;
                 end.
                 """)]
+    [InlineData("""
+                program main;
+                procedure test;
+                begin
+                end;
+                begin
+                end.
+                """)]
+    [InlineData("""
+                program main;
+                               function test(a, b : integer) : integer;
+                               begin
+                               test := 1;
+                               end;
+                               begin
+                               end.
+                """)]
+    [InlineData("""
+                program main;
+                var i : integer;
+                begin
+                for i := 1 to 100 do
+                begin
+                doSomething(i);
+                end;
+                end.
+                """)]
+    [InlineData("""
+                program main;
+                begin
+                if 1 = 2 then
+                begin
+                test1;
+                test2 := a;
+                end
+                else
+                begin
+                doSomething;
+                end;
+                end.
+                """)]
+    [InlineData("""
+                program main;
+                var a : integer;
+                function test : integer;
+                begin
+                end;
+                begin
+                test;
+                a := test;
+                test();
+                a := test();
+                end.
+                """)]
+    [InlineData("""
+                program main;
+                procedure test();
+                begin
+                end;
+                begin
+                test();
+                end.
+                """)]
+    [InlineData("""
+                program main;
+                begin
+                test
+                end.
+                """)]
     public void ProgramParseTest(string input)
     {
         ProgramParse(input);
diff --git a/CanonSharp.Tests/ParserTests/StatementParserTests.cs b/CanonSharp.Tests/ParserTests/StatementParserTests.cs
index b54ef27..b4bc86b 100644
--- a/CanonSharp.Tests/ParserTests/StatementParserTests.cs
+++ b/CanonSharp.Tests/ParserTests/StatementParserTests.cs
@@ -83,6 +83,46 @@ public class StatementParserTests : GrammarParserTestBase
         Assert.Equal("a", assignNode.Variable.Identifier.LiteralValue);
     }
 
+    [Fact]
+    public void ProcedureCallTest1()
+    {
+        ProcedureCallNode node = RunParser<ProcedureCallNode>(GrammarParser.ProcedureCallParser(), "test()");
+        Assert.Equal("test", node.Identifier.LiteralValue);
+        Assert.Empty(node.Parameters);
+
+        node = RunParser<ProcedureCallNode>(GrammarParser.ProcedureCallParser(), "test");
+        Assert.Equal("test", node.Identifier.LiteralValue);
+        Assert.Empty(node.Parameters);
+    }
+
+    [Fact]
+    public void ProcedureCallTest2()
+    {
+        ProcedureCallNode node = RunParser<ProcedureCallNode>(GrammarParser.ProcedureCallParser(),
+            "test(1 + 1, true)");
+
+        Assert.Equal(2, node.Parameters.Count);
+
+        BinaryOperatorNode firstParameter = node.Parameters[0].Convert<BinaryOperatorNode>();
+        Assert.Equal(BinaryOperatorType.Add, firstParameter.OperatorType);
+
+        BooleanValueNode secondParameter = node.Parameters[1].Convert<BooleanValueNode>();
+        Assert.True(secondParameter.Value);
+    }
+
+    [Fact]
+    public void ProcedureCallTest3()
+    {
+        ProcedureCallNode node =
+            RunParser<ProcedureCallNode>(GrammarParser.ProcedureCallParser(), "test(1 * + 1, test2[0])");
+
+        Assert.Equal(2, node.Parameters.Count);
+
+        VariableNode secondParameter = node.Parameters[1].Convert<VariableNode>();
+        Assert.Equal("test2", secondParameter.Identifier.LiteralValue);
+        Assert.Single(secondParameter.Indexers);
+    }
+
     [Theory]
     [InlineData("""
                 begin
diff --git a/CanonSharp.Tests/ParserTests/SubprogramParserTests.cs b/CanonSharp.Tests/ParserTests/SubprogramParserTests.cs
new file mode 100644
index 0000000..c5fa723
--- /dev/null
+++ b/CanonSharp.Tests/ParserTests/SubprogramParserTests.cs
@@ -0,0 +1,83 @@
+using CanonSharp.Pascal.Parser;
+using CanonSharp.Pascal.SyntaxTree;
+using CanonSharp.Tests.Utils;
+
+namespace CanonSharp.Tests.ParserTests;
+
+public class SubprogramParserTests : GrammarParserTestBase
+{
+    [Fact]
+    public void ParameterTest1()
+    {
+        List<Parameter> parameters = RunParser<Parameter>(GrammarParser.ParameterParser(), "a ,b : integer");
+
+        Assert.Equal(2, parameters.Count);
+        Assert.All(parameters, p =>
+        {
+            Assert.False(p.IsReference);
+            Assert.Equal("integer", p.TypeNode.Convert<TypeNode>().TypeToken.LiteralValue);
+        });
+
+        parameters = RunParser<Parameter>(GrammarParser.ParameterParser(), "var a, b,c: real");
+        Assert.Equal(3, parameters.Count);
+        Assert.All(parameters, p =>
+        {
+            Assert.True(p.IsReference);
+            Assert.Equal("real", p.TypeNode.Convert<TypeNode>().TypeToken.LiteralValue);
+        });
+    }
+
+    [Theory]
+    [InlineData("(var a, b : integer; c, d : real)", 4)]
+    [InlineData("(a : boolean; var c, d, e : char)", 4)]
+    [InlineData("(a : integer)", 1)]
+    [InlineData("(var b ,c : real)", 2)]
+    public void FormalParameterTest(string input, int count)
+    {
+        List<Parameter> parameters = RunParser<Parameter>(GrammarParser.FormalParameterParser(), input);
+        Assert.Equal(count, parameters.Count);
+    }
+
+    [Theory]
+    [InlineData("procedure test", 0)]
+    [InlineData("procedure test()", 0)]
+    [InlineData("procedure test(a : integer; var b : real)", 2)]
+    [InlineData("procedure test(a,b, c : real; var e, f : boolean)", 5)]
+    [InlineData("function test : integer", 0)]
+    [InlineData("function test() : real", 0)]
+    [InlineData("function test(a : integer; var b : real) : boolean", 2)]
+    [InlineData("function test(a,b, c : real; var e, f : boolean) : char", 5)]
+    public void SubprogramHeadTest(string input, int count)
+    {
+        SubprogramHead head = RunParser<SubprogramHead>(GrammarParser.SubprogramHeadParser(), input);
+        Assert.Equal(count, head.Parameters.Count);
+    }
+
+    [Fact]
+    public void SubprogramHeadTest1()
+    {
+        SubprogramHead head =
+            RunParser<SubprogramHead>(GrammarParser.SubprogramHeadParser(), "function test(a : integer) : real");
+
+        Assert.Equal("test", head.Identifier.LiteralValue);
+        Assert.Single(head.Parameters);
+        Assert.NotNull(head.TypeToken);
+        Assert.Equal("real", head.TypeToken.Convert<TypeNode>().TypeToken.LiteralValue);
+    }
+
+    [Fact]
+    public void SubprogramBodyTest1()
+    {
+        SubprogramBody body = RunParser<SubprogramBody>(GrammarParser.SubprogramBodyParser(), """
+            const a = 3;
+            var c, d : integer; e, f :real;
+            begin
+                c := a + d;
+            end
+            """);
+
+        Assert.Single(body.ConstDeclarations.Statements);
+        Assert.Equal(2, body.VariableDeclarations.Statements.Count);
+        Assert.Equal(1, body.MainBlock.Statements.Count);
+    }
+}