Abstract: 120 Kda and 70 Kda protein in the larval midgut membrane of the lepidopteran Helicoverpa armigera identified as putative receptor for Bt Cry 1Ac delta-endotoxin .Receptor proteins have been purified by a combination of gel-filtration and anion exchange chromatography .In ligand-blotting experiment ,the purified protein has binding capacity with Cry 1Ac and Cry 1Ab but not to Cry 2A .N-terminal sequence obtained from the protein show no homology to already existing sequences .When assayed for amino-peptidase and alkaline phosphatase activities , purified receptors preparations were enriched 2.5 fold in amino-peptidase activity compare to Helicoverpa-armigera brush border membrane vesicles . The 70 Kda protein seems to be the part of 120 Kda receptor protein.