IsNumeric() is not foolproof. For example, see if "00100e2" passes IsNumeric().<BR><BR>That's because "e" has mathematical meaning, and so the entire number CAN be a number. It could, actually, be 0010000. Which IS numeric. So it passes.<BR><BR>Regular expressions are much better, but are a more expensive operation - see Ran's post below.<BR><BR>Craig.