HANK,

Use CF with the Formula Is option, with a formula like

=NOT(ISERROR(MATCH(B2,K:K,False)))

where B2 is the activecell at the time that you apply the formatting.

And if the empty cells are turning red and your want to prevent that....

=AND(B2<"",NOT(ISERROR(MATCH(B2,K:K,False))))

HTH,
Bernie
MS Excel MVP


"HANK" wrote in message
...
I have two columns of numbers. One small set (25-200, imported daily) of
numbers in column B, and 8365 unique numbers in column K. I would like to
use conditional formatting to tell me if any of the numbers imported into
column B match any of the 8365 unique numbers in column K. If so, I would
like the numbers in column B that match to turn Red.