The distribution and content of Cry1Ab insecticidal protein in different tissues of the Asian corn borer, Ostrinia furnacalis (Guenée), when the 3rd instar larvae of Cry1Ab protein resistant and susceptible colonies fed on whorl leaves of Bt-transgenic corn expressing Cry1Ab protein for 3 days were determined and analyzed by enzyme-linked immunosorbent assay  (ELISA). The distributions of Cry1Ab in different tissuesin the resistant and susceptible larvae were similar, mainly in the midgut tissue and haemolymph. The Cry1Ab contents in the midgut tissues of the resistant larvae with and without contents inside their midguts were 277.2 ng/g and 52.7 ng/g, respectively, significantly higher than those of the susceptible larvae, which were 104.9 ng/g and 40.1 ng/g, respectively. The Cry1Ab contents in the haemolymph of the resistant and susceptible larvae were 93.7 ng/g and 69.5 ng/g, respectively. The Cry1Ab protein in the silk gland and Malpighian tubules in the resistant and susceptible larvae could be detected, but the concentration was quite low. No Cry1Ab protein was detected in the fat body and reproductive organs, pupae, adults and eggs by ELISA method both in the resistant and susceptible larvae fed on the Bt corn. The results suggested that the Cry1Ab protein from larvae feeding on Bt corn could not be biotransferred to the subsequent pupae, adults and eggs.