This code will require cell A1 of Sheet1 be filled in before the file will be saved.
HTH,
Bernie
MS Excel MVP
Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
If Worksheets("Sheet1").Range("A1").Value = "" Then
MsgBox "Fill in cell A1 on Sheet1 !!!!"
Cancel = True
MsgBox "File is not saved yet!"
End If
End Sub