diff --git a/common/changes/office-ui-fabric-react/master_2018-05-08-02-09.json b/common/changes/office-ui-fabric-react/master_2018-05-08-02-09.json
new file mode 100644
index 0000000000000..c131957538deb
--- /dev/null
+++ b/common/changes/office-ui-fabric-react/master_2018-05-08-02-09.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "packageName": "office-ui-fabric-react",
+      "comment": "BaseButton: Allow Alt + Down on menu buttons to open the menu",
+      "type": "patch"
+    }
+  ],
+  "packageName": "office-ui-fabric-react",
+  "email": "chiechan@microsoft.com"
+}
\ No newline at end of file
diff --git a/packages/office-ui-fabric-react/src/components/Button/BaseButton.tsx b/packages/office-ui-fabric-react/src/components/Button/BaseButton.tsx
index 2363f38db1e71..895d5194fa414 100644
--- a/packages/office-ui-fabric-react/src/components/Button/BaseButton.tsx
+++ b/packages/office-ui-fabric-react/src/components/Button/BaseButton.tsx
@@ -450,7 +450,7 @@ export class BaseButton extends BaseComponent<IBaseButtonProps, IBaseButtonState
 
   private _openMenu = (shouldFocusOnContainer?: boolean): void => {
     if (this.props.menuProps) {
-      const menuProps = {...this.props.menuProps, shouldFocusOnContainer: shouldFocusOnContainer };
+      const menuProps = { ...this.props.menuProps, shouldFocusOnContainer: shouldFocusOnContainer };
       if (this.props.persistMenu) {
         menuProps.hidden = false;
       }
@@ -679,13 +679,13 @@ export class BaseButton extends BaseComponent<IBaseButtonProps, IBaseButtonState
   private _isValidMenuOpenKey(ev: React.KeyboardEvent<HTMLDivElement | HTMLAnchorElement | HTMLButtonElement>): boolean {
     if (this.props.menuTriggerKeyCode) {
       return ev.which === this.props.menuTriggerKeyCode;
-    } else {
-      if (this._isSplitButton) {
-        return ev.which === KeyCodes.down && (ev.altKey || ev.metaKey);
-      } else {
-        return ev.which === KeyCodes.enter;
-      }
+    } else if (this.props.menuProps) {
+      return ev.which === KeyCodes.down && (ev.altKey || ev.metaKey);
     }
+
+    // Note: When enter is pressed, we will let the event continue to propagate
+    // to trigger the onClick event on the button
+    return false;
   }
 
   private _onMenuClick = (ev: React.MouseEvent<HTMLDivElement | HTMLAnchorElement>) => {