Hello there, I wrote a specific perl script to split a fasta database in files of (aprox) equal size. I test with a "nt" database and it looks good Check this out and tell me what you think, I hope you find this useful http://www.labmc.inf.utfsm.cl/~san/Bio_Inf/download/cortar.pl Greetings, -- Sergio Antonio Ahumada N <san@inf.utfsm.cl> Centro de Biotecnologia - UTFSM