Not from within a formula but you can use sheet event code.
Assuming you had a formula in A1 that reads =IF(B1="","",B1)
Private Sub Worksheet_Calculate()
On Error GoTo endit
Application.EnableEvents = False
If Me.Range("A1") = "" Then
macroname
End If
endit:
Application.EnableEvents = True
End Sub
Right-click on the sheet tab and "View Code". Copy/paste to the sheet module.
Note: will not fire if A1 is just blank as in contents cleared.
For that you would need something like this.
Private Sub Worksheet_Change(ByVal Target As Range)
On Error GoTo endit
Application.EnableEvents = False
If Me.Range("A1") = "" Then
macroname
End If
endit:
Application.EnableEvents = True
End Sub
Gord Dibben MS Excel MVP