Control of the pink bollworm, Pectinophora gossypiella (Saunders) in Southern California is dependent almost entirely on repeated applications of insecticides. During the past few years, the synthetic pyrethroids have been used quite extensively, especially when other insects, as Heliothis spp., were present. There have been reports where properly applied treatments of synthetic pyrethroids did not give the desired level of control that was achieved in previous years or was expected. Resistance was suspected. Susceptibility of moths from a problem field at Brawley, California to 3 insecticides was determined by topical application and the LD-50's compared to a laboratory strain and to moths from a field in Arizona which had not been treated for several years and resistance was not suspected. Results show that the LD-50 of the Brawley moths for permethrin were 21-fold and 5.6-fold greater than the LD-50 for the susceptible field and the laboratory strain, respectivley. Fenvalerate showed less differences and there were little or no differences in the LD-50's for azinphosmethyl. Permethrin was the most commonly used insecticide in the problem field during 1984. Thus it appears that the pink bollworm has developed some resistance to permethrin in the Brawley area of Southern California.