Thalassemias are considered important health issues throughout Iraq, involving its Kurdistan region. This disorder, particularly its major form, needs lifelong regular transfusions. But this form of medical care is associated with various complications including red cell alloimmunization and autoimmunization. This study determined the frequency and associations of alloimmunization among multi-transfused patients with -thalassemia major. The subjects were 204 patients who were registered at a thalassemia care center in Sulaymaniyah-Iraqi Kurdistan. The patients' records were analyzed, their red cells were phenotyped for ABO/RhD antigens using the gel card method, and irregular antibody screening/identification was performed using the standard tube method. Alloantibodies were detected in 5.8% of the patients, while DAT was positive in 4% of the patients, which indicated autoantibodies. The identified alloantibodies were anti-E (2.4%), anti-C (1.4%), anti-e (1%), and anti-K (1%). A patient's age at the start of transfusion (＞2 years) (P=0.042) and a positive history of transfusion reactions (P=0.003) were correlated with a significantly higher rate of alloantibody formation. From the results of our study, we conclude that measures to decrease the development of alloantibodies may incorporate matching for Rhesus and Kell systems and early induction of blood transfusions.