Data was taken on 13 to 15 farms in the Mississippi Delta in 1997, 1998, and 1999 to measure the entomological and economic impact of Bt cotton when compared with conventional cotton. Data from 1997 showed that insect control costs were slightly less for conventional cotton. In 1998, data showed that in the face of a heavier tobacco budworm problem, there was a significant reduction in insect control costs for Bt cotton. In 1999, all cotton insect problems were very low and the data indicated a smaller cost for insect control in conventional cotton.