diff --git a/common/changes/@hcengineering/text-markdown/fix-markdown-inline-comment-mark_2026-05-28-13-02.json b/common/changes/@hcengineering/text-markdown/fix-markdown-inline-comment-mark_2026-05-28-13-02.json
new file mode 100644
index 0000000..7021822
--- /dev/null
+++ b/common/changes/@hcengineering/text-markdown/fix-markdown-inline-comment-mark_2026-05-28-13-02.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Fix markdown serialization for inline comment marks.",
+      "type": "patch",
+      "packageName": "@hcengineering/text-markdown"
+    }
+  ],
+  "packageName": "@hcengineering/text-markdown",
+  "email": "igor.loskutoff@gmail.com"
+}
diff --git a/packages/text-markdown/src/__tests__/markdown.test.ts b/packages/text-markdown/src/__tests__/markdown.test.ts
index 1068e7b..d905ee2 100644
--- a/packages/text-markdown/src/__tests__/markdown.test.ts
+++ b/packages/text-markdown/src/__tests__/markdown.test.ts
@@ -1100,6 +1100,32 @@ describe('markupToMarkdown', () => {
           }
         ]
       }
+    },
+    {
+      name: 'inline comment mark',
+      markdown: 'commented text',
+      markup: {
+        type: MarkupNodeType.doc,
+        content: [
+          {
+            type: MarkupNodeType.paragraph,
+            content: [
+              {
+                type: MarkupNodeType.text,
+                text: 'commented text',
+                marks: [
+                  {
+                    type: 'inline-comment',
+                    attrs: {
+                      thread: 'thread-1'
+                    }
+                  }
+                ]
+              }
+            ]
+          }
+        ]
+      }
     }
   ]
 
diff --git a/packages/text-markdown/src/serializer.ts b/packages/text-markdown/src/serializer.ts
index ed49060..ab0e186 100644
--- a/packages/text-markdown/src/serializer.ts
+++ b/packages/text-markdown/src/serializer.ts
@@ -421,6 +421,13 @@ export const storeMarks: Record<string, MarkProcessor> = {
     mixable: false,
     expelEnclosingWhitespace: false,
     escape: false
+  },
+  'inline-comment': {
+    open: '',
+    close: '',
+    mixable: false,
+    expelEnclosingWhitespace: false,
+    escape: true
   }
 }