thank you for your reply I'll study and test your code (which is a bit obscure to me up to now); by the way do you think that "merge_all" is a wrong way to hit? thanks again m -- View this message in context: http://r.789695.n4.nabble.com/merge-multiple-data-frames-tp4331089p4331830.html Sent from the R help mailing list archive at Nabble.com.