A few studies have been done about echocardiographic changes during hemodialysis and after renal transplantation. In this prospective research project, 76 hemodialysis patients and 32 renal transplant recipients (RTLs) were studied for about 17 months .The systolic and diastolic function of left ventricle and their changes, LV mass index (LVMI) and its changes, pattern of LV hypertrophy and valvular disorders evaluated in each group and compared. The frequency of regional wall motion abnormality (RWMA) and abnormal ejection fraction (EF<50%) increased in hemodialysis patients. The peak E wave velocity and E/A ratio decreases in RTRs but increased in hemodialysis patients. LVIM elevated in the hemodialysis patients (p<0.0001). There was not my significant correlation between LVMI and hemoglobin, creatinine, urea or albumin. LVMI changes had a significant correlation with the systolic, diastolic and mean blood pressure of hemodialysis patients but not with RTRs. The most common pattern of ventricular hypertrophy on RTRs was concentric hypertrophy but in hemodialysis patients was mixed hypertrophy. Prevalence and severity of aortic and mitral insufficiency increased in hemodialysis patients but decreased in RTRs. Probably due to continuous increase of volume and pressure overload and humoral factors. LVMI increases in hemodialysis patients, whereas in RTRs at least does not increase. The RWMA and abnormal EF in the hemodialysis patients suggest a progressive left ventricular failure. Due to persistent volume and pressure overload in hemodialysis patients, the frequency of aortic and mitral insufficiency increase. Finally, it can be suggested that in comparison to hemodialysis patients, RTRs have better cardiac function. To approve this theory, more advanced studies are needed. Key Words: Echocardiography-hemodialysis-renal transplantation-systolic function-diastolic function.