Prophylactic spraying of storage surfaces with insecticides is the safest and most efficient method of grain protection. Studies were conducted to evaluate the efficacy of bifenthrin, when used for disinfecting ware houses and jute sacks, against four different stored grain pests, i.e. Sitophilus oryzae, Tribolium castaneum, Trogoderma granarium and Rhyzopertha dominica, at Hyderabad, Andhra Pradesh, India during 2004. Toxicological studies under laboratory conditions revealed that the LD₅₀ values of bifenthrin against S. oryzae, T. castaneum, T. granarium and R. dominica were 3.389, 46.65, 4.509 and 5.573, respectively, when treated on concrete slabs and 4.629, 48.0, 5.056 and 6.042, respectively, when treated on jute strips. The investigations revealed that bifenthrin, when used for prophylactic control, is effective only against S. oryzae, T. granarium and R. dominica but not against T. castaneum.