The wild-type Cry1Ie gene from Bacillus thuringiensis was modified for its efficient expression in transgenic plants. Modified Cry1Ie gene (designated as Cry1Iem) was cloned into prokaryotic expression vector pET28b and its expression in E. coli was confirmed by SDS-PAGE analysis. Bioassays using crude expression products in E. coli revealed that Cry1Iem protein had a similar toxicity to corn borer as wild-type Cry1Ie. Cry1Iem gene was then inserted downstream of the maize ubiquitin-1 promoter in plant expression vector p3301. Transgenic tobacco plants carrying Cry1Iem showed insecticidal activity against corn borer.