Pretreatment of cotton seeds with tested herbicides markedly increased resistance of cotton plants to Verticillium wilt caused by Verticillium dahliae. The present investigation studied the effect of three herbicides tested on mycelial growth of V. dahliae and induction of gossypol synthesis of cotton cells. All herbicides selected had inhibitory effect on the mycelial growth of the pathogen particularly at high concentrations. Prometryn caused a great reduction in the appearance of Verticillium wilt disease and was the most effective in controlling the disease. Maximum amounts of gossypol production were also observed in roots and stems of prometryn-treated plants. Protection of gossypol was greater in treated and V. dahliae-inoculated than in treated and uninoculated plants.