Sub aa()
Dim chemin As String
Dim WB As Workbook
chemin = "C:\Documents and Settings\Patrick\Bureau\wmi.xls" 'à adapter
On Error Resume Next
Set WB = Workbooks(Mid(chemin, InStrRev(chemin, "\") + 1))
If Err <> 0 Then
Set WB = Workbooks.Open(Filename:=chemin)
Err.Clear
End If
On Error GoTo 0
End Sub