To assess the usefulness of dipyridamole thallium perfusion imaging in the evaluation of myocardial perfusion in hemodialysis (HD), we studied 29 HD patients divided into three groups: A) 13 patients with clinical angina, B) 8 patients without angina but similar in age, sex, time on HD and hematocrit and C) 8 young asymptomatic patients (mean age 33 +/- 9.7 years). Dipyridamole thallium-201 (Tl-201) perfusion imaging revealed myocardial perfusion defects in 8 patients (61%) from group A, 4 (50%) from group B and 1 (12.5%) from group C. These defects were localized in the inferior, posterior and septal segments of the left ventricle. Abnormal myocardial perfusion was associated with age over 50 years and aortic calcifications (p less than 0.05). Eight patients died within the following four years. All had aortic calcifications (p less than 0.001). Our results show that myocardial perfusion defects are frequent even in non-symptomatic HD patients. This suggests that ischemic heart disease could be more frequent than estimated by clinical symptoms alone. Tl-201 scintigraphy may be a useful non-invasive procedure in cardiological evaluation of HD patients.