Strains of the tobacco budworm, Heliothis virescens (F.), and bollworm, Helicoverpa zea (Boddie), collected in Mississippi were evaluated in bioassays to four classes of insecticides, and mixtures of insecticides and a synergist. High and intermediate levels of resistance were found to cypermethrin and thiodicarb, respectively, in H. virescens. No increased tolerance was seen to profenofos in H. virescens and no increased tolerance to any insecticide tested was detected in H. zea. Significant resistance to Bacillus thuringiensis Berliner was not observed in either species during the season. No synergism was detected in a bioassay using insecticide mixtures and piperonyl butoxide on a resistant strain of H. virescens. Multiple resistance in H. virescens is still evident and resistance to pyrethroids appears to be stabilized.