The effect of Parkinson's disease (PD) on young patients' lives is likely to differ from that in older patients. For this study, 75 patients with onset of PD before the age of 50 and 66 patients with later onset completed a booklet of questionnaires on demographic and clinical variables, quality of life, and psychosocial factors. Apart from a higher rate of treatment-related dyskinesias in the younger onset group, the two groups did not differ in self-reported disease severity or disability. A higher percentage of young-onset patients was unemployed due to disability or had retired early. Quality of life as measured on the PDQ-39 was significantly worse in young-onset patients than in older-onset patients. Young-onset patients also had worse scores on the stigma and marital satisfaction scales, and were depressed more frequently. Differences between the two groups in their most commonly employed coping strategies and in terms of their satisfaction with emotional support did not reach significance. We conclude that young-onset patients more frequently experience loss of employment, disruption of family life, greater perceived stigmatization, and depression than do older-onset patients with PD. In addition to more severe treatment-related motor complications, social and psychosocial factors may contribute to greater impairment of quality of life in young patients with PD.