Apomorphine disruption of prepulse inhibition (PPI) has been proposed as an animal model of sensorimotor gating deficits exhibited by schizophrenics. The effects of apomorphine on PPI of the acoustic startle reflex in male rats of Wistar and CD (Sprague-Dawley derived) strains were compared under identical test conditions. In Wistar rats, subcutaneous administration of 0.25-1.0 mg/kg apomorphine blocked PPI without affecting startle amplitude. In CD rats, apomorphine (0.3-3.0 mg/kg, SC) had no effect on PPI, but increased startle amplitude. Therefore, choice of rat strain is an important factor in the design of experiments studying apomorphine effects on PPI.