A 1,4-benzodiazepine, SC-32855, was administered orally once daily at doses of 30, 100, and 300 mg/kg for two weeks to adult Beagle dogs (1/sex/dose). The 300 mg/kg animals were sacrificed in extremis on day three after showing extreme signs of CNS depression. At necropsy, the testes of the 100 mg/kg male weighed considerably less than those of the control. The testicular weights of the 30 and 300 mg/kg animals were comparable to the weight of the control testes. Histopathologic evaluation of the testes of the 100 mg/kg male revealed degenerative and necrotic changes in the seminiferous tubules and cytoplasmic vacuolation in Leydig cells. In the 30 and 300 mg/kg animals, degenerative and necrotic changes were restricted to the seminiferous tubules.