Field and laboratory tests were conducted to determine the toxicity of profenofos in combination with cyhalothrin to larvae of the tobacco budworm, Heliothis virescens (F.). In a field test, full, half, and quarter rate insecticide mixtures of profenofos and cyhalothrin were compared with full and half rates of each compound separately. Toxicity data were obtained with first and third instar tobacco budworm larvae. Data demonstrated that half rate insecticide mixtures of profenofos and cyhalothrin provided approximately equal control to full rates of each compound separately. Laboratory bioassays of each insecticide only and in combination are in progress. Although further research is needed, data suggest that using mixtures of profenofos and cyhalothrin at low rates will reduce selection pressure on the tobacco budworm, thus decreasing selection for resistance to pyrethroids and organophosphates.