Latent inhibition (LI) is an attentional process by which animals learn to ignore a stimulus that is repeatedly presented without reinforcement. This ability to tune out a motivationally irrelevant stimulus is disrupted by pharmacological manipulations producing hyperdopaminergic states. In Experiment I, LI was disrupted following five daily administrations of 4 mg/kg d-amphetamine. In Experiment II the disruptive effects of d-amphetamine were eliminated by concomitant administration of chlorpromazine. Experiment III showed that LI could also be disrupted with 1 mg/kg d-amphetamine coupled with dopamine receptor supersensitivity produced by prolonged pretreatment with haloperidol. These data suggest that pharmacological disruption of LI may provide an animal analogue of the defective stimulus filtering thought to characterize at least some forms of schizophrenia.