The aim of this study was the effect of vitamin D supplementation on cardiac output, pulmonary artery pressure, serum ferritin and blood pressure in patients with thalassemia major is. This study is a clinical trial 33 patients with thalassemia referred to thalassemia ward has Exclusion criteria: other concurrent diseases, including heart disease; Diabetes; Hepatitis; Hypo-parathyroid; Less than 35% of cardiac output method selected by convenience sampling thalassemia major, iron overload is that they have no heart or sediment are mild, measured levels of vitamin D, ferritin and blood pressure measurement is performed. In case of low vit D of 74 nmol l or 29 ng per ml, is studied. The patients underwent echocardiography and cardiac output are measured and also vitamin D3 during the twelve week treatment at a dose of 50,000 IU per week begins. After 3 months, the level of vitamin D, ferritin and blood pressure were measured and in case of normal vitamin D levels, the second echo is done. Low vitamin D in vitamin D treatment will be repeated once again. Patients with improved cardiac output, blood pressure, pulmonary blood pressure ferritin levels are considered to be responding to treatment