Drug-induced psychosis represents one of the more serious adverse effects of therapy for Parkinson's disease. Risk factors include dementia, a history of psychiatric illness, advancing age, and the dose and duration of treatment with dopamine-enhancing agents.The pathophysiological basis of drug-induced psychosis has not been established. Chronic changes in both the dopaminergic and serotonergic systems have been implicated in producing these symptoms.Management options include the reduction and/or elimination of medications used for symptomatic control of the illness. However, with the attendant risks of an unacceptable reduction in mobility and, in rare cases, life-threatening complications, therapeutic alternatives are required. Treatment with atypical antipsychotic agents, such as clozapine and risperidone, presents such an avenue. Nonpharmacological treatments, including electroconvulsive therapy (ECT), may also play a role in the management of these patients.