During a 13-month period, 9 patients with phencyclidine-induced psychosis were admitted to Darnall Army Hospital. They exhibited hostility agitation, and tangentiality and had delusions of influence and religious grandiosity. Six subjects reported auditory hallucinations, and 4 were disoriented in at least 1 sphere. Despite treatment with antipsychotic medication, the psychotic episodes often persisted for more than 30 days. Our clinical finding of prolonged psychotic reactions, together with previous reports of the effects of phencyclidine, suggests that phenycyclidine provides an intriguing drug model for schizophrenia.