This report presents the results of a comparison between information obtained from response to the question "Have you been told that the diabetes has affected the back of your eyes, that is, the retina?" and the determination of the severity of retinopathy by grading of stereoscopic fundus photographs. Both "younger onset" (n = 996) and "older onset" (n = 1,370) persons who participated in a large population-based study of diabetic persons in southern Wisconsin from 1980-1982 were included. For the younger onset persons, 31.1% responded positively, while 70.7% were found to have retinopathy. The sensitivity of the questionnaire response varied from 17.8% for persons with mild nonproliferative retinopathy to 81.9% for persons with proliferative retinopathy. The specificity was 97.3%. For the older onset persons, 14.9% responded positively, while 54.2% were found to have retinopathy. The sensitivity of the question varied from 9.9% for persons with mild nonproliferative retinopathy to 68.7% for persons with proliferative retinopathy. The specificity was 93.3%. The question used in this survey provides a highly specific measure of prevalence; it is most sensitive for proliferative retinopathy.