Despite the high prevalence of Parkinson's disease (PD) in the elderly, little information is available regarding the epidemiology of the disease in residents in long-term care facilities. Using a population-based database with over 470,000 residents (1992-1996) of all Medicare- or Medicaid-certified nursing homes of five states, we identified 24,402 residents with a diagnosis of PD. We examined data collected with the federally mandated Minimum Data Set, and sociodemographic, clinical, and treatment information. The prevalence of PD in nursing homes was 5.2%, with peak age-specific prevalence between ages 75 and 84 years. Seventy percent of patients had moderate to severe cognitive impairment, and over 80% had moderate to severe functional disability. Less than 10% had verbal and physical signs of grief and anxiety, and 80% exhibited poor psychosocial well-being, yet only 15% were actively treated for depression. Only 44% received antiparkinsonian drugs. Female gender, black race, age, level of cognitive impairment, and level of physical functioning were inversely related to the likelihood of receiving one of these drugs. When antipsychotic drugs were administered (15%), only 1% were atypical agents. Although PD is a relatively common diagnosis among nursing home residents, pharmacologic management of these individuals appears to be less than optimal.