Parkinson's disease (PD) is a movement disorder characterized by progressive degeneration of central dopaminergic systems. Current therapies designed to augment dopaminergic neurotransmission effectively treat the motoric aspects of the disease, however, with prolonged use, they produce a range of treatment-limiting side effects. Of these, neuropsychiatric abnormalities including hallucinosis and psychosis are common, disabling and refractory to most current therapies. This review describes the clinical syndrome of psychosis in PD and data regarding the efficacy and tolerability of existing antipsychotic agents, and presents the scientific rationale for the development of serotonin 2A receptor inverse agonists as potential therapeutic agents for treatment-induced psychosis of PD.