Try this...
[green]'Module[/green][blue]
Public Declare Function SendMessageByString Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As String) As Long
Public Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Public Const WM_CLOSE = &H10[/blue]
[green]'Form[/green][blue]
Private Sub Command1_Click()
Dim xlmain As Long
xlmain = FindWindow("xlmain", vbNullString)
Call SendMessageByString(xlmain, WM_CLOSE, 0&, 0&)
End Sub[/blue]
If you know the filename open in excel you can use..
[blue]
Private Sub Command1_Click()
Dim xlmain As Long
xlmain = FindWindow("xlmain", "microsoft excel - book1"

Call SendMessageByString(xlmain, WM_CLOSE, 0&, 0&)
End Sub[/blue]
Good Luck!