Field studies were conducted at three locations in Mississippi in 2000 and one location in 2001 to determine the advantages of cotton expressing two insecticidal proteins of Bacillus thuringiensis over cotton expressing only one Bt toxin. In 2000, five total insecticide applications for heliothines were required for all locations, but only in non-Bt plots. In 2001, four applications were needed (one location), but as in 2000, only in non-Bt plots. There was no difference in yield between non- Bt, single-toxin, and dual-toxin Bt cotton for experiments. Insect pest populations were relatively light in both years of the experiment, resulting in no advantage of Bollgard II cotton over the original Bt cotton technology. In 2000, the cost of Bt cotton technology exceeded the cost of foliar insecticides; thus, non-Bt cotton would have been more profitable than either of the Bt cottons, due to similar yields. In 2001, however, since there was an increased number of insecticide applications for lepidopteran pests in non-Bt cotton, Bt cottons were more of a cost-effective alternative.