Create a new .exe project and in the load event of form1 put: Const MF_BYPOSITION = &H400 Private Declare Function GetSystemMenu Lib "User32" _ (ByVal hWnd As Long, ByVal bRevert _ As Long) As Long Private Declare Function RemoveMenu Lib "User32" _ (ByVal hMenu As Long, ByVal nPosition _ As Long, ByVal wFlags As Long) As Long Private Sub Form_Load()     RemoveMenu GetSystemMenu(Me.hWnd, 0), 6, MF_BYPOSITION End Sub Execute the app. (F5) and you`ll see the X ("close") button is disabled