If you create a GUI that's always on top, you need to make sure to make the MsgBox a child of the GUI by passing the GUI's handle to the MsgBox function... Local $hGUI = GUICreate("My GUI", -1, -1, -1, -1, -1, $WS_EX_TOPMOST) MsgBox($MB_OK, "Child Window!", "Hey look! I'm on top!", 0, $hGUI)