You can use the FORMULA IS option under conditional formatting. Use a
formula like

=COUNTIF($A$1:$A$999,B1)0

if you're referencing another worksheet, you must use indirect

=COUNTIF(INDIRECT("Sheet1!$A$1:$A$999"),B1)0



"Fred Timmons" wrote in message
...
I am managing a do-not-call list with a large contact
database. How do I establish a poitive/negative match
from source data.
eg. Cell D7 value is: 212-555-1212.
The source worksheet has a list of all phone numbers in
Column A.
So, if the value of Cell D7 matches a value in source
worksheet Column A, I can conditionally format it.
Thanks in advance.