Using the National Center of Health Statistics' mortality statistics databases for 1991 through 1996 (12,430,473 deaths), we isolated 144,364 individuals 40 years of age or older with a primary diagnosis of Parkinson's disease (PD). Of these, 122 died by suicide. The rate of suicide in the general population was about 10 times higher than in patients with PD (0.8% compared with only 0.08%, respectively). These different rates of suicide cannot be attributed to differences in age, gender, race, education, or marital status. Compared with patients with suicidal PD, patients with PD who died from other causes manifested significantly lower rates of affective disorders. The referent population exhibited a higher rate of malignancy and a lower rate of depression. The findings suggest that marital status, mood disorder, and somatic comorbidity provide only a limited understanding of completed suicide.