Hi!

Try this:

This is an array formula and needs to be entered using the key combination
of CTRL,SHIFT,ENTER:

=SUM(N(FREQUENCY(IF(A1:A5="W",MATCH(C1:C5,C1:C5,0) ),MATCH(C1:C5,C1:C5,0))0))

Biff

"Greg" wrote in message
...
I'd like to count the number of unique occurences in column C providing
column A = "W".
Col A ColB ColC
W c D
X d Z
L d X
W c Z
W c Z
The answer I'm looking for is 2.
Thanks, Greg