Introduction: Beta-thalassemia major (BTM) is an autosomal recessive disease characterized by hemolytic anemia. Increased iron load accumulating in the body as a result of frequent erythrocyte transfusions leads to endothelial dysfunction and cardiovascular complications. High asymmetric dimethylarginine (ADMA) levels disrupt 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. Materials and 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, reticulocyte count, serum ferritin and the iron level, liver, renal function tests, plasma ADMA and endocan, and proBNP. Cardiac examination results were evaluated on all children in both patient and control groups by a pediatric cardiologist. Results: Mean ADMA level in the BTM group is higher than in the control group. Endocan levels in patients with BTM were not found to be statistically different. Serum endocan and ADMA levels were not associated with cardiovascular functions. Conclusion: Although serum levels of ADMA were found to be significantly higher in BTM patients, high serum endocan and ADMA levels were not associated with cardiovascular functi-ons.