Hi,

Because it is a calculated value you can use the worksheet calculate event

Private Sub Worksheet_Calculate()
If Range("A1").Value < 100 Then
MsgBox "Cell value " & Range("A1").Value
End If
End Sub

Mike

"Stuart M" wrote:

Cell validation only works when data is entered directly in a cell. I want to
recreate this effect so that Excel displays a pop up message when the
calculated value of a cell falls below £100. The cell in question is
calculating the sum of three other cells on the worksheet and is formatted as
currency.

Cheers :)