Albino rats of the Sprague-Dawley strain exhibited an unusual sex incidence to audiogenic seizures, with females more susceptible than males. It was predicted that altering the sex hormone balance by means of surgical intervention or hormonal injection would alter their seizure susceptibility. Male rats were castrated and then received injections of estradiol (100 RU) and progesterone (0.5 mg). Female rats received testosterone (1.0 and 2.0 mg) and were later ovariectomized. Audiogenic seizure tests under two threshold conditions were conducted prior to and during the respective hormonal treatments. Each group was used as its own control. The results indicated that castration of the males had little effect on seizure responses. Estradiol administration resulted in an increase in seizure responses. In the females, testosterone administration and ovariectomy resulted in a decrease in seizure responses. It was concluded that sex hormones either exert a direct effect or mediate the control of audiogenic seizure responses in rats of the Sprague-Dawley strain.