Hi John
use the following formula to check for an open workbook:
Function IsWorkbookOpen(Name As String)
Dim WB As Workbook
On Error Resume Next
Set WB = Workbooks(Name)
On Error GoTo 0
IsWorkbookOpen = Not (WB Is Nothing)
End Function

so you can then use the following
Sub Check_WB()
If IsWorkbookOpen("Book1.xls") Then
Workbooks("Book1.xls").Close
Else
Workbooks.Open Filename:="D:\temp\Book1.xls"
End If
End Sub

HTH
Frank

John Baker wrote:
HI:

I would like to test if a specific file is open, and if it is I want
to close it. Can someone tell me the expression to use to deterine is
a file (say collector.xls) is open?

Thank you

John Baker