You associate a pair of check-mark bitmaps with a menu item by passing the handles of the bitmaps to the SetMenuItemBitmaps function. The hBitmapUnchecked parameter identifies the unchecked bitmap, and the hBitmapChecked parameter identifies the checked bitmap. If you want to remove one or both check marks from a menu item, you can set the hBitmapUnchecked or hBitmapChecked parameter, or both, to NULL.