Based on your sample data, to get the unique count of names in a specific
month/year...

Array entered** :

=SUM(IF(FREQUENCY(IF(TEXT(F2:F9,"mmmyyyy")="Oct200 8",MATCH(K2:K9,K2:K9,0)),ROW(K2:K9)-ROW(K2)+1),1))

** array formulas need to be entered using the key combination of
CTRL,SHIFT,ENTER (not just ENTER). Hold down both the CTRL key and the SHIFT
key then hit ENTER.

Assumes no empty cells in the name range.

The formula above will count for Oct 2008.

--
Biff
Microsoft Excel MVP


"Irelandabroad" wrote in message
...
I have a worksheet with several columns:

Column F Column K
21/10/2008 Smith
27/10/2008 Jones
28/10/2008 Smith
25/11/2008 Jones
3/12/2008 Johns
10/02/2009 Johns
2/06/2009 Ryan
4/02/2009 Ryan

I need to prepare a formula which will count the number of times each
unique
name appears in a month. (i have several years of data)

Thanks