Background/Aims: This study examined the role of diabetes mellitus on determining left ventricular function by evaluating coronary artery diameter in patients with end-stage renal disease on maintenance hemodialysis treatment. Methods: We studied 12 diabetic and 12 nondiabetic patients on maintenance hemodialysis treatment without significant stenoses of the major epicardial coronary arteries. Patients were matched for age, sex distribution, duration of dialysis and incidence of major coronary risk factors. Left ventricular wall thickness (septal and posterior walls) and left ventricular diameter (end-diastolic and systolic phases), were measured by echocardiography. Hemodynamic measurements and coronary angiography were performed on the day of hemodialysis and coronary artery diameter at the proximal and mid portion of three major coronary arteries were measured using the computed densitometry method. Results: Right and left anterior descending and circumflex coronary artery diameters were all significantly smaller and the frequency of coronary artery calcification was higher in diabetic (58%) compared to nondiabetic (8%) patients. Although there were no significant differences in left ventricular wall thickness, left ventricular diameter, mean right atrial pressure and cardiac index between the two groups, left ventricular end-diastolic pressure was significantly higher in diabetic (22 ± 9 mm Hg) compared to nondiabetic patients (14 ± 5 mm Hg). Conclusion: Despite that there were no significant stenoses of the major epicardial coronary arteries, diffuse luminal narrowing of the epicardial coronary arteries in diabetic patients on maintenance hemodialysis treatment was associated with increased left ventricular end-diastolic pressure.