In summer 2000, adult female bollworm moths were collected from various light-trap locations near Tidewater Research Station, Plymouth, NC. Female moths were allowed to lay eggs; and at hatch, 24 larvae from each female were screened on each of three diets: non- B.t., CryIA(c), and CryIIAa at 5.0 ug toxin per milliliter of diet. These screens were performed to isolate any resistance genes present in the field populations of bollworm. We found 1 individual out of 583 screened that appeared to carry a major gene for resistance to CryIA(c). Assuming four genomes per individual, then the gene frequency is 1/2332 or 0.00043. Other females appeared to have minor genes for CryIA(c) resistance or major genes with lower levels of dominance. We also found 1 individual out of 646 screened that appeared to carry a major gene for resistance to CryIIAa. The gene frequency for CryIIAa resistance would be estimated at 1/2584 or 0.00039. Again, other females seemed to carry minor resistance genes. Along with results reporting partially dominant inheritance of CryIA(c) resistance, these estimates may be important when instituting refuge areas for the sustainability of transgenic cotton.