Field experiments have been carried out to evaluate the potency of the biological control agent Bacillus thuringiensis (Dipel), the pyrethroid Fenvalerate and their combinations for the control of the lesser cotton leafworm Spodoptera exigua on soybeans in Qualubia governorate. Molasses was combined with all treatments to enhance their effectiveness. One spray application with either Dipel or Fenvalerate showed an obvious reduction in larval counts of S. exigua, associated with a signifi-cant increase in the crop yield but in varying degrees, in correlation with the tested dose. Treatments with combinations of both biological and chemi-cal insecticides at the lowest tested doses (62 g of B. t. ± 50 ml of Fenvalerate/feddan) showed to be highly potential, and caused 2.8 fold increase in the crop yield. It may be recommended that a combination of both preparations may be used for the control of S. exigua.