Let's say you have a very large Excel spreadsheet and you want to identify all the rows that have duplicate values in a particular column. For this example we will assume that the 'A' column has the values you want to look at. We also assume the data starts on row 2 and goes to row 1000. - insert a column ('B') - in B2 put the following formula: =countif(A$2:A$1000, a2)>1 - copy the contents of B2 to the range B3:B1000 - now select row 1 and turn on auto-filter (Data > Filter > AutoFilter) - finally, filter in the B column for all TRUE values The listed rows are the ones that have duplicate values in the 'A' column. Variations on this tip will follow I'm sure ;) Regards, Jeff