if that doesn't work, maybe also try: if x is your data frame with length a columns, "unique(x[,1:a])". ----- Lanna Jin lannajin at gmail.com 510-898-8525 -- View this message in context: http://r.789695.n4.nabble.com/Delete-rows-with-duplicate-field-tp2123939p2123964.html Sent from the R help mailing list archive at Nabble.com.