Greg,
Excel normally does not recalculate functions if their inputs have not
changed.
But may be application.Volatile will give the desired behaviour.

NickHK

"Greg Longtin" wrote in message
...
Tim,

What are the inputs to the UDF? Does it use any data not passed as a
parameter?

One cell value, which is the name a worksheet in the workbook to use for
the
calculation.

Greg