I understand that if you press Cancel or OK without typing anything then an InputBox function returns a zero length string, but how do you determine which of the two buttons was pressed?

What you could do if you wanted to use an input box rather than a user defined form (UDF) is to set the default value for the input box to " " (space) rather than a zero length string. If the user clicks OK then a space is passed, if Cancel then a zero lenth string is paased.

I would strongly suggest the use of a UDF if you want to recognise the click properties of different buttons.

Cheers

Matt