Phencyclidine (PCP) abuse usually causes a short, self-limited period of intoxication but may lead to a prolonged psychosis, poorly responsive to antipsychotic medications. Prior reports indicate that electroconvulsive therapy (ECT) is a safe, rapidly effective treatment in such cases, but longer-term outcome has not been studied. We report three cases of PCP-associated psychosis that did not respond to at least 2 weeks of antipsychotic treatment but subsequently responded rapidly to ECT. Follow-up at 14 to 21 months after treatment show that recovery was maintained except in one subject who relapsed after continuing to abuse PCP. ECT should be considered as a treatment early in the course of drug-associated psychoses in which an adequate trial of antipsychotic medication has not been effective.