To examine the possible role of environmental factors in the cause of Parkinson's disease (PD), we reviewed mortality trends for PD in the United States from 1962 through 1984. We found that age-specific mortality for PD in all demographic groups had changed notably during this 23-year interval. Among whites of both sexes, substantial declines were observed among the middle-aged, while notable increases were seen in the geriatric age groups. Similar changes were found in nonwhites; among nonwhites in the geriatric age range, increases of 22% to 553% were observed among women. Men generally had a 100% higher risk of death due to PD than did women. Whites were at three times the risk of nonwhites. The observed temporal changes appear to reflect improved treatment, better case ascertainment, and a true rise in the incidence of PD, particularly among the elderly. This rise may be due to preventable environmental causes and will require further investigation.