PURPOSE. To evaluate the prevalence of diabetic retinopathy and risk factors among patients with self-reported diabetes mellitus in China. METHODS. The Beijing Eye Study, a population-based study on inhabitants aged 40+ years, included 4439 subjects. Fundus photographs of the worse eye from participants with self-reported diabetes were graded. RESULTS. Fundus photographs ready for evaluation and a filled out questionnaire were available for 4127 (93.0%) subjects. The prevalence of self-reported diabetes was 235/4127 (5.7%). Among the subjects with a self-reported diagnosis of diabetes, diabetic retinopathy was detected on the fundus photographs of 86 (37.1%) subjects, with macular edema in 12 (5.2%) subjects, clinically significant macular edema in 6 (2.6%) subjects, and a vision- threatening stage of the retinopathy in 12 (5.2%) subjects. Diabetic retinopathy was associated with rural region (p=0.004), longer duration of diabetes (p=0.009), use of diabetic medications (p=0.02), and lower education background (p=0.003). CONCLUSIONS. Prevalence of diabetic retinopathy among Chinese patients aged 40+ years with a self-reported diagnosis of diabetes is about 37%, with a vision-threatening stage of the retinopathy detected in 5% of the subjects. About 5.7% of the adult Chinese population report on a known diagnosis of diabetes mellitus, with about 15% of these subjects knowing about the presence of diabetic retinopathy. The frequency of known diabetes mellitus is lower in rural regions than in urban regions, while diabetic retinopathy overall and macular edema among the subjects with known diabetes mellitus were significantly more common in the rural group. (Eur J Ophthalmol 2009; 19: 91-9)