Hi, I think that rettype for the section "Get GIs for a list of accessions" should be -rettype => 'gi'); instead of 'gilist' as it is now. I think this change is due to a change in NCBI eutils. webpage: http://www.bioperl.org/wiki/HOWTO:EUtilities_Cookbook#Get_GIs_for_a_list_of_accessions Thanks, Shyam