diff --git a/packages/devextreme/js/__internal/ui/chat/chat_message_box.ts b/packages/devextreme/js/__internal/ui/chat/chat_message_box.ts
index 9e8ca0f07003..a4bf3c4ca420 100644
--- a/packages/devextreme/js/__internal/ui/chat/chat_message_box.ts
+++ b/packages/devextreme/js/__internal/ui/chat/chat_message_box.ts
@@ -77,6 +77,7 @@ class MessageBox extends DOMComponent<MessageBox, Properties> {
       stylingMode: 'outlined',
       placeholder: 'Type a message',
       autoResizeEnabled: true,
+      maxHeight: '20em',
     });
   }
 
diff --git a/packages/devextreme/testing/tests/DevExpress.ui.widgets/chatParts/messageBox.tests.js b/packages/devextreme/testing/tests/DevExpress.ui.widgets/chatParts/messageBox.tests.js
index 6dff928d3f1e..4f77abefc440 100644
--- a/packages/devextreme/testing/tests/DevExpress.ui.widgets/chatParts/messageBox.tests.js
+++ b/packages/devextreme/testing/tests/DevExpress.ui.widgets/chatParts/messageBox.tests.js
@@ -60,6 +60,7 @@ QUnit.module('MessageBox', moduleConfig, () => {
                 stylingMode: 'outlined',
                 placeholder: 'Type a message',
                 autoResizeEnabled: true,
+                maxHeight: '20em',
             };
 
             const textArea = TextArea.getInstance(this.$textArea);