Background: Beta-thalassemia major (BTM) is an autosomal recessive disease characterized by hemolytic anemia. Increased iron load accumulated in the body as a result of frequent erythrocyte transfusions leads to endothelial dysfunction and cardiovascular complications. High asymmetric dimethylarginine (ADMA) levels disrupts endothelial function. Endocan is a soluble proteoglycan synthesized in vascular endothelial cells in many organs. High levels of endocan indicate endothelial dysfunction. We aimed to determine whether there is a correlation with cardiac evaluation instruments by evaluating circulating ADMA and endocan levels in BTM patient group and healthy control group and whether they can be a prognostic marker in terms of endothelial dysfunction and cardiovascular risk stratification. Methods: A total of 39 patients with BTM and 39 age and gender matched healthy children were enrolled in the study. Medical histories of all patients were recorded and physical examinations were performed. Complete blood count, reticulocytic count, serum ferritin and iron level, liver, renal function tests, plasma ADMA and endocan and proBNP. Cardiac examination results by a pediatric cardiologist were tested on all children in both patient and control groups. Results: Mean ADMA in the BTM group is higher than in the control group. Endocan levels in patients with BTM were not found to be statistical difference (337,5±344,0 pg/mL vs 218,14±171,1 pg/mL) (p=0,057). Serum endocan and ADMA levels were not associated with cardiovascular functions. Conclusions: Although serum levels of endocan were found to be significantly higher in BTM patients, high serum endocan and ADMA levels were not associated with cardiovascular functions.