diff --git a/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java b/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
index ced5fc1..4ba5b6f 100644
--- a/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
+++ b/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
@@ -39,18 +39,23 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitProgram(KlangParser.ProgramContext ctx) {
-    FunctionDefinition[] funcs = new FunctionDefinition[ctx.functionDef().size()];
+    var typeCheckedFunctionDefs = new FunctionDefinition[ctx.functionDef().size()];
+    var typeCheckedStructDefs = new HashMap<String, StructDefinition>();
 
     for (int i = 0; i < ctx.functionDef().size(); i++) {
-      funcs[i] = (FunctionDefinition) this.visit(ctx.functionDef(i));
+      typeCheckedFunctionDefs[i] = (FunctionDefinition) visit(ctx.functionDef(i));
     }
 
-    Expression expression = (Expression) this.visit(ctx.expression());
-    Program result = new Program(funcs, structDefs, enumDefs, expression);
-    result.type = expression.type;
-    result.line = ctx.start.getLine();
-    result.col = ctx.start.getCharPositionInLine();
-    return result;
+    for (int i = 0; i < ctx.structDef().size(); i++) {
+      typeCheckedStructDefs.put(ctx.structDef(i).structName.getText(), (StructDefinition) visit(ctx.structDef(i)));
+    }
+
+    var expression = (Expression) visit(ctx.expression());
+    var program = new Program(typeCheckedFunctionDefs, typeCheckedStructDefs, enumDefs, expression);
+    program.type = expression.type;
+    program.line = ctx.start.getLine();
+    program.col = ctx.start.getCharPositionInLine();
+    return program;
   }
 
   @Override
@@ -727,6 +732,46 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     return n;
   }
 
+  @Override
+  public Node visitStructDef(KlangParser.StructDefContext ctx) {
+    var structName = ctx.structName.getText();
+    var structFieldCount = ctx.structField().size();
+    var structFields = new StructField[structFieldCount];
+    var line = ctx.start.getLine();
+    var col = ctx.start.getCharPositionInLine();
+
+    for (int i = 0; i < structFieldCount; i++) {
+      structFields[i] = (StructField) visit(ctx.structField(i));
+    }
+
+    var structDef = new StructDefinition(structName, structFields);
+    structDef.type = Type.getByName(structName);
+    structDef.line = line;
+    structDef.col = col;
+
+    return super.visitStructDef(ctx);
+  }
+
+  @Override
+  public Node visitStructField(KlangParser.StructFieldContext ctx) {
+    var structFieldName = ctx.IDENT().getText();
+    var structFieldType = Type.getByName(ctx.type_annotation().type().getText());
+    var line = ctx.start.getLine();
+    var col = ctx.start.getCharPositionInLine();
+
+    if (!structFieldType.isPrimitiveType() && !structDefs.containsKey(structFieldType.getName()) && !enumDefs.containsKey(structFieldType.getName())) {
+      var error = "Type " + structFieldType.getName() + " not defined.";
+      throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
+    }
+
+    var structField = new StructField(structFieldName);
+    structField.type = structFieldType;
+    structField.line = line;
+    structField.col = col;
+
+    return structField;
+  }
+
   @Override
   public Node visitFunctionDef(KlangParser.FunctionDefContext ctx) {
     String name = ctx.funcName.getText();
diff --git a/src/test/java/ParameterTest.java b/src/test/java/ParameterTest.java
deleted file mode 100644
index 9342ccc..0000000
--- a/src/test/java/ParameterTest.java
+++ /dev/null
@@ -1,14 +0,0 @@
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-
-import org.antlr.v4.runtime.tree.ParseTree;
-import org.junit.jupiter.api.Test;
-
-public class ParameterTest {
-    @Test
-    void typeNotDefined() {
-        ParseTree tree = Helper.prepareParser("struct test { a: schwurbel; } function foo(): int { return 1; } foo();");
-        Exception e = assertThrows(RuntimeException.class, () -> Helper.getStructs(tree));
-        assertEquals("Error in line 1:14 Type schwurbel not defined.", e.getMessage());
-    }
-}
\ No newline at end of file
diff --git a/src/test/java/StructDefinitionTest.java b/src/test/java/StructDefinitionTest.java
new file mode 100644
index 0000000..b3150f3
--- /dev/null
+++ b/src/test/java/StructDefinitionTest.java
@@ -0,0 +1,62 @@
+import de.hsrm.compiler.Klang.ContextAnalysis;
+import de.hsrm.compiler.Klang.GetDefinitions;
+import org.junit.jupiter.api.Test;
+
+import java.util.HashMap;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class StructDefinitionTest {
+    @Test
+    void shouldNotThrowIfStructIsWellDefined() {
+        // given
+        var tree = Helper.prepareParser("struct test { a: int; } function foo(): int { return 1; } foo();");
+        var ctxAnal = new ContextAnalysis(Helper.getFuncs(tree), Helper.getStructs(tree), Helper.getEnums(tree));
+
+        // when / then
+        assertDoesNotThrow(() -> ctxAnal.visit(tree));
+    }
+
+    @Test
+    void shouldNotThrowIfStructFieldTypeIsReferringToEnum() {
+        // given
+        var tree = Helper.prepareParser("struct test { a: bar; } enum bar {A,B,C} function foo(): int { return 1; } foo();");
+        var ctxAnal = new ContextAnalysis(Helper.getFuncs(tree), Helper.getStructs(tree), Helper.getEnums(tree));
+
+        // when / then
+        assertDoesNotThrow(() -> ctxAnal.visit(tree));
+    }
+
+    @Test
+    void shouldThrowExceptionIfStructFieldTypeIsNotDefined() {
+        // given
+        var tree = Helper.prepareParser("struct test { a: schwurbel; } function foo(): int { return 1; } foo();");
+        var ctxAnal = new ContextAnalysis(Helper.getFuncs(tree), Helper.getStructs(tree), Helper.getEnums(tree));
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
+        assertEquals("Error in line 1:14 Type schwurbel not defined.", e.getMessage());
+    }
+
+    @Test
+    void shouldThrowExceptionIfStructFieldTypeIsReferringToAFunction() {
+        // given
+        var tree = Helper.prepareParser("struct test { a: foo; } function foo(): int { return 1; } foo();");
+        var ctxAnal = new ContextAnalysis(Helper.getFuncs(tree), Helper.getStructs(tree), Helper.getEnums(tree));
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
+        assertEquals("Error in line 1:14 Type foo not defined.", e.getMessage());
+    }
+
+    @Test
+    void shouldThrowExceptionIfStructFieldNameIsDuplicated() {
+        // given
+        var tree = Helper.prepareParser("struct test { a: int; a: bool; } function foo(): int { return 1; } foo();");
+        var getDefs = new GetDefinitions(new HashMap<>(), new HashMap<>(), new HashMap<>());
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> getDefs.visit(tree));
+        assertEquals("Error in line 1:22 Duplicate struct field a in struct test.", e.getMessage());
+    }
+}
\ No newline at end of file