diff --git a/demos/classchart.html b/demos/classchart.html
index b20dda2a3..508bb1066 100644
--- a/demos/classchart.html
+++ b/demos/classchart.html
@@ -154,6 +154,29 @@
     </pre>
     <hr />
 
+    <pre class="mermaid">
+    classDiagram
+      A1 --> B1
+      namespace A {
+        class A1 {
+          +foo : string
+        }
+        class A2 {
+          +bar : int
+        }
+      }
+      namespace B {
+        class B1 {
+          +foo : bool
+        }
+        class B2 {
+          +bar : float
+        }
+      }
+      A2 --> B2
+    </pre>
+    <hr />
+
     <script type="module">
       import mermaid from './mermaid.esm.mjs';
       mermaid.initialize({
diff --git a/packages/mermaid/src/diagrams/class/classDb.ts b/packages/mermaid/src/diagrams/class/classDb.ts
index 11a1eb37d..7b74aa819 100644
--- a/packages/mermaid/src/diagrams/class/classDb.ts
+++ b/packages/mermaid/src/diagrams/class/classDb.ts
@@ -448,9 +448,8 @@ const getNamespaces = function (): NamespaceMap {
 export const addClassesToNamespace = function (id: string, classNames: string[]) {
   if (namespaces[id] !== undefined) {
     classNames.map((className) => {
+      classes[className].parent = id;
       namespaces[id].classes[className] = classes[className];
-      delete classes[className];
-      classCounter--;
     });
   }
 };
diff --git a/packages/mermaid/src/diagrams/class/classDiagram.spec.ts b/packages/mermaid/src/diagrams/class/classDiagram.spec.ts
index a43ed2fcd..2182e8c34 100644
--- a/packages/mermaid/src/diagrams/class/classDiagram.spec.ts
+++ b/packages/mermaid/src/diagrams/class/classDiagram.spec.ts
@@ -1373,9 +1373,54 @@ class Class2
       parser.parse(str);
 
       const testNamespace = parser.yy.getNamespace('Namespace1');
+      const testClasses = parser.yy.getClasses();
       expect(Object.keys(testNamespace.classes).length).toBe(2);
       expect(Object.keys(testNamespace.children).length).toBe(0);
       expect(testNamespace.classes['Class1'].id).toBe('Class1');
+      expect(Object.keys(testClasses).length).toBe(2);
+    });
+
+    it('should add relations between classes of different namespaces', function () {
+      const str = `classDiagram
+      A1 --> B1
+      namespace A {
+        class A1 {
+          +foo : string
+        }
+        class A2 {
+          +bar : int
+        }
+      }
+      namespace B {
+        class B1 {
+          +foo : bool
+        }
+        class B2 {
+          +bar : float
+        }
+      }
+      A2 --> B2`;
+
+      parser.parse(str);
+      const testNamespaceA = parser.yy.getNamespace('A');
+      const testNamespaceB = parser.yy.getNamespace('B');
+      const testClasses = parser.yy.getClasses();
+      const testRelations = parser.yy.getRelations();
+      expect(Object.keys(testNamespaceA.classes).length).toBe(2);
+      expect(testNamespaceA.classes['A1'].members[0]).toBe('+foo : string');
+      expect(testNamespaceA.classes['A2'].members[0]).toBe('+bar : int');
+      expect(Object.keys(testNamespaceB.classes).length).toBe(2);
+      expect(testNamespaceB.classes['B1'].members[0]).toBe('+foo : bool');
+      expect(testNamespaceB.classes['B2'].members[0]).toBe('+bar : float');
+      expect(Object.keys(testClasses).length).toBe(4);
+      expect(testClasses['A1'].parent).toBe('A');
+      expect(testClasses['A2'].parent).toBe('A');
+      expect(testClasses['B1'].parent).toBe('B');
+      expect(testClasses['B2'].parent).toBe('B');
+      expect(testRelations[0].id1).toBe('A1');
+      expect(testRelations[0].id2).toBe('B1');
+      expect(testRelations[1].id1).toBe('A2');
+      expect(testRelations[1].id2).toBe('B2');
     });
   });
 
diff --git a/packages/mermaid/src/diagrams/class/classRenderer-v2.ts b/packages/mermaid/src/diagrams/class/classRenderer-v2.ts
index e0cfea641..6197fe8ac 100644
--- a/packages/mermaid/src/diagrams/class/classRenderer-v2.ts
+++ b/packages/mermaid/src/diagrams/class/classRenderer-v2.ts
@@ -93,52 +93,51 @@ export const addClasses = function (
   log.info(classes);
 
   // Iterate through each item in the vertex object (containing all the vertices found) in the graph definition
-  keys.forEach(function (id) {
-    const vertex = classes[id];
+  keys
+    .filter((id) => classes[id].parent == parent)
+    .forEach(function (id) {
+      const vertex = classes[id];
 
-    /**
-     * Variable for storing the classes for the vertex
-     */
-    let cssClassStr = '';
-    if (vertex.cssClasses.length > 0) {
-      cssClassStr = cssClassStr + ' ' + vertex.cssClasses.join(' ');
-    }
+      /**
+       * Variable for storing the classes for the vertex
+       */
+      const cssClassStr = vertex.cssClasses.join(' ');
 
-    const styles = { labelStyle: '', style: '' }; //getStylesFromArray(vertex.styles);
+      const styles = { labelStyle: '', style: '' }; //getStylesFromArray(vertex.styles);
 
-    // Use vertex id as text in the box if no text is provided by the graph definition
-    const vertexText = vertex.label ?? vertex.id;
-    const radius = 0;
-    const shape = 'class_box';
+      // Use vertex id as text in the box if no text is provided by the graph definition
+      const vertexText = vertex.label ?? vertex.id;
+      const radius = 0;
+      const shape = 'class_box';
 
-    // Add the node
-    const node = {
-      labelStyle: styles.labelStyle,
-      shape: shape,
-      labelText: sanitizeText(vertexText),
-      classData: vertex,
-      rx: radius,
-      ry: radius,
-      class: cssClassStr,
-      style: styles.style,
-      id: vertex.id,
-      domId: vertex.domId,
-      tooltip: diagObj.db.getTooltip(vertex.id, parent) || '',
-      haveCallback: vertex.haveCallback,
-      link: vertex.link,
-      width: vertex.type === 'group' ? 500 : undefined,
-      type: vertex.type,
-      // TODO V10: Flowchart ? Keeping flowchart for backwards compatibility. Remove in next major release
-      padding: getConfig().flowchart?.padding ?? getConfig().class?.padding,
-    };
-    g.setNode(vertex.id, node);
+      // Add the node
+      const node = {
+        labelStyle: styles.labelStyle,
+        shape: shape,
+        labelText: sanitizeText(vertexText),
+        classData: vertex,
+        rx: radius,
+        ry: radius,
+        class: cssClassStr,
+        style: styles.style,
+        id: vertex.id,
+        domId: vertex.domId,
+        tooltip: diagObj.db.getTooltip(vertex.id, parent) || '',
+        haveCallback: vertex.haveCallback,
+        link: vertex.link,
+        width: vertex.type === 'group' ? 500 : undefined,
+        type: vertex.type,
+        // TODO V10: Flowchart ? Keeping flowchart for backwards compatibility. Remove in next major release
+        padding: getConfig().flowchart?.padding ?? getConfig().class?.padding,
+      };
+      g.setNode(vertex.id, node);
 
-    if (parent) {
-      g.setParent(vertex.id, parent);
-    }
+      if (parent) {
+        g.setParent(vertex.id, parent);
+      }
 
-    log.info('setNode', node);
-  });
+      log.info('setNode', node);
+    });
 };
 
 /**
diff --git a/packages/mermaid/src/diagrams/class/classTypes.ts b/packages/mermaid/src/diagrams/class/classTypes.ts
index cf6f20f0b..f3b8dc8cf 100644
--- a/packages/mermaid/src/diagrams/class/classTypes.ts
+++ b/packages/mermaid/src/diagrams/class/classTypes.ts
@@ -7,6 +7,7 @@ export interface ClassNode {
   members: string[];
   annotations: string[];
   domId: string;
+  parent?: string;
   link?: string;
   linkTarget?: string;
   haveCallback?: boolean;