You can always use the FindWindow-function and the PostMessage-function to find the wanted application, and then send it a message that it has to close itself. One disadvantage: you'll need the exact caption of this application. Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long Private Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long Const WM_CLOSE = &H10 Private Sub Form_Load() Dim winHwnd As Long Dim RetVal As Long winHwnd = FindWindow(vbNullString, "Calculator") If winHwnd <> 0 Then PostMessage winHwnd, WM_CLOSE, 0&, 0& Else MsgBox "The Calculator is not open." End If End Sub