Background: Apelin, a newly discovered adipocytokine, is produced by white adipose tissue and is also expressed in the kidney and heart. Increasing evidence suggests a role for apelin in the pathology of the cardiovascular system. Cardiovascular disease is a major contributor to the mortality and morbidity in patients with chronic renal failure. The aim of this study was to assess effect of hemodialysis and renal transplantation on plasma apelin level and to find possible correlations between apelin and echocardiographic parameters in hemodialyzed patients. Patients and Methods: We investigated plasma apelin levels (using commercially available kits) in 40 adult subjects: a group of 15 (12 males, 3 females) hemodialyzed patients scheduled for renal transplantation (group 1), a group of 15 (11 males, 4 females) hemodialyzed patients on regular dialysis treatment for ESRD (group 2) and a group 10 (6 males, 4 females) healthy control subjects (group 3). An echocardiography was performed for all subjects. Results: We found that plasma apelin levels are reduced in hemodialyzed patients. Plasma apelin was also found to be positively correlated with LVESD, RV and LA in our ESRD patients included in the study. Regarding the effect of hemodialysis on plasma apelin levels we found that there is no significant effect, while levels increased two weeks after successful kidney transplantation. Conclusions: Apelin level was significantly lower in dialyzed patients and it correlated significantly with some echocardiographic parameters in these patients, thus it might be involved in the pathophysiology of cardiovascular disease in chronic renal failure. Hemodialysis has no significant effect on plasma apelin levels, while two weeks after kidney transplantation, apelin concentrations were significantly elevated, however, they were still below normal values of healthy controls. Since apelin is an inotrope in normal and failing hearts, this finding may have clinical implications for future use of apelin as a novel inotropic agent for patients with uremic cardiomyopathy.