diff --git a/packages/mermaid/src/diagrams/class/classDb.ts b/packages/mermaid/src/diagrams/class/classDb.ts
index 48ef7ccbe..851353477 100644
--- a/packages/mermaid/src/diagrams/class/classDb.ts
+++ b/packages/mermaid/src/diagrams/class/classDb.ts
@@ -392,6 +392,29 @@ const setDirection = (dir: string) => {
   direction = dir;
 };
 
+/**
+ * Function called by parser when a namespace keyword has been found.
+ *
+ * @param id - Id of the namespace to add
+ * @public
+ */
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+export const addNamespace = function (id: string) {
+  // TODO: Implement here
+};
+
+/**
+ * Function called by parser when a namespace definition has been found.
+ *
+ * @param id - Id of the namespace to add
+ * @param classNames - Ids of the class to add
+ * @public
+ */
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+export const addClassesToNamespace = function (id: string, classNames: string[]) {
+  // TODO: Implement here
+};
+
 export default {
   parseDirective,
   setAccTitle,
@@ -425,4 +448,6 @@ export default {
   setDiagramTitle,
   getDiagramTitle,
   setClassLabel,
+  addNamespace,
+  addClassesToNamespace,
 };
diff --git a/packages/mermaid/src/diagrams/class/classDiagram.spec.ts b/packages/mermaid/src/diagrams/class/classDiagram.spec.ts
index 24fbc41ea..11b556179 100644
--- a/packages/mermaid/src/diagrams/class/classDiagram.spec.ts
+++ b/packages/mermaid/src/diagrams/class/classDiagram.spec.ts
@@ -571,6 +571,37 @@ foo()
       const str = 'classDiagram\n' + 'note "test"\n';
       parser.parse(str);
     });
+
+    it('should handle "namespace"', function () {
+      const str = `classDiagram
+namespace Namespace1 { class Class1 }
+namespace Namespace2 { class Class1
+}
+namespace Namespace3 {
+class Class1 {
+int : test
+string : foo
+test()
+foo()
+}
+}
+namespace Namespace4 {
+class Class1 {
+int : test
+string : foo
+test()
+foo()
+}
+class Class2 {
+int : test
+string : foo
+test()
+foo()
+}
+}
+`;
+      parser.parse(str);
+    });
   });
 
   describe('when fetching data from a classDiagram it', function () {
diff --git a/packages/mermaid/src/diagrams/class/parser/classDiagram.jison b/packages/mermaid/src/diagrams/class/parser/classDiagram.jison
index 4e68372f3..1c0ccdbbe 100644
--- a/packages/mermaid/src/diagrams/class/parser/classDiagram.jison
+++ b/packages/mermaid/src/diagrams/class/parser/classDiagram.jison
@@ -21,6 +21,8 @@
 %x acc_descr_multiline
 %x class
 %x class-body
+%x namespace
+%x namespace-body
 %%
 \%\%\{                                                          { this.begin('open_directive'); return 'open_directive'; }
 .*direction\s+TB[^\n]*                                          return 'direction_tb';
@@ -48,9 +50,20 @@ accDescr\s*"{"\s*                                { this.begin("acc_descr_multili
 "classDiagram"          return 'CLASS_DIAGRAM';
 "[*]"                   return 'EDGE_STATE';
 
-"class"                     { this.begin('class'); return 'CLASS';}
+<INITIAL,namespace>"namespace"  { this.begin('namespace'); return 'NAMESPACE'; }
+<namespace>\s*(\r?\n)+          { this.popState(); return 'NEWLINE'; }
+<namespace>\s+                  /* skip whitespace */
+<namespace>[{]                  { this.begin("namespace-body"); return 'STRUCT_START';}
+<namespace-body>[}]             { this.popState(); return 'STRUCT_STOP'; }
+<namespace-body><<EOF>>         return "EOF_IN_STRUCT";
+<namespace-body>\s*(\r?\n)+     return 'NEWLINE';
+<namespace-body>\s+             /* skip whitespace */
+<namespace-body>"[*]"           return 'EDGE_STATE';
+
+<INITIAL,namespace-body>"class"     { this.begin('class'); return 'CLASS';}
 <class>\s*(\r?\n)+          { this.popState(); return 'NEWLINE'; }
 <class>\s+                  /* skip whitespace */
+<class>[}]                  { this.popState(); this.popState(); return 'STRUCT_STOP';}
 <class>[{]                  { this.begin("class-body"); return 'STRUCT_START';}
 <class-body>[}]             { this.popState(); return 'STRUCT_STOP'; }
 <class-body><<EOF>>         return "EOF_IN_STRUCT";
@@ -264,6 +277,11 @@ classLabel
     : SQS STR SQE { $$=$2; }
     ;
 
+namespaceName
+    : alphaNumToken { $$=$1; }
+    | alphaNumToken namespaceName { $$=$1+$2; }
+    ;
+
 className
     : alphaNumToken { $$=$1; }
     | classLiteralName { $$=$1; }
@@ -275,6 +293,7 @@ className
 statement
     : relationStatement       { yy.addRelation($1); }
     | relationStatement LABEL { $1.title =  yy.cleanupLabel($2); yy.addRelation($1);        }
+    | namespaceStatement
     | classStatement
     | methodStatement
     | annotationStatement
@@ -288,6 +307,21 @@ statement
     | acc_descr_multiline_value  { $$=$1.trim();yy.setAccDescription($$); }
     ;
 
+namespaceStatement
+    : namespaceIdentifier STRUCT_START classStatements STRUCT_STOP          {yy.addClassesToNamespace($1, $3);}
+    | namespaceIdentifier STRUCT_START NEWLINE classStatements STRUCT_STOP  {yy.addClassesToNamespace($1, $4);}
+    ;
+
+namespaceIdentifier
+    : NAMESPACE namespaceName   {$$=$2; yy.addNamespace($2);}
+    ;
+
+classStatements
+    : classStatement                            {$$=[$1]}
+    | classStatement NEWLINE                    {$$=[$1]}
+    | classStatement NEWLINE classStatements    {$3.unshift($1); $$=$3}
+    ;
+
 classStatement
     : classIdentifier                                    
     | classIdentifier STYLE_SEPARATOR alphaNumToken      {yy.setCssClass($1, $3);}