Among 236 non-insulin-dependent diabetics with clinically suspected coronary artery disease, the rate of thallium-201 myocardial perfusion defects was significantly higher in subjects with (40.6%) than without (22.1%) diabetic retinopathy. Retinopathy was associated with a higher risk of perfusion defects in subjects with cardiac and noncardiac chest pain, and may thus be a useful marker for selecting patients in whom thallium scintigraphy screening is warranted.