Abstract: We constructed previously the expressing library of Leishmania donovani genomic DNA with λgt11 as vector.In this paper, 2×10 4 phages were plated on E. coli Y 1090r , and screened with a rabbit antiserum prepared by immunization with Leishmania donovani promastigotes.Bound antibodies were detected using alkaline phosphatase labeled anti rabbit antibodies.A positive expressing clone was detected and transferred into E.coli Y 1098r to prepare lysate,a 39 kDa polypeptide in E.coli Y 1089r lysate was recognized by anti Leishmania donovani serum.The result indicated that the 39 kDa polypeptide which was not fused with the major portion of β galactosidase existed disconnectedly.This finding remained to be further studied.