For more than one criteria use SUMPRODUCT
=SUMPRODUCT(--(Sheet2!A1:A100="A5/2"),--(Sheet2!B1:B100="OP"))
for details see
http://www.xldynamic.com/source/xld.SUMPRODUCT.html

http://mcgimpsey.com/excel/formulae/doubleneg.html

An alternative for you is Pivot Table
best wishes
--
Bernard V Liengme
www.stfx.ca/people/bliengme
remove caps from email

"Richard" wrote in message
...
I am using Excel 2000 and Windows XP. I have 2 worksheets. The first
worksheet has the formula I am trying to create. The second worksheet has
2
columns, the first column has the values A5/4, A6/4 etc. the second column
has various values eg OP, BS etc I am trying to use COUNTIF in the first
worksheet to count the number of times A5/4 AND OP occurs in the same row.

Many thanks in advance.
--
Richard