Forty-nine patients with Type I diabetes mellitus were assessed to examine the relationship between lifetime prevalence of psychiatric illness and retinopathy severity. The subjects with a history of psychiatric illness had significantly worse retinopathy than the subjects without psychiatric illness. Eighty-nine percent of the subjects with severe nonproliferative retinopathy or proliferative retinopathy had a history of psychiatric illness, predominantly affective illness. In addition, the subjects with a history of psychiatric illness had significantly higher current glycohemoglobin levels than those with no psychiatric history. This study's findings suggest that psychiatric illness may be a risk factor for development of retinopathy in Type I diabetic patients.