摘要:Background: Development of alloantibodies against the foreign red blood cell (RBC) (alloimmunization) is a well-known complication in thalassemia patients when performing multiple transfusions. The study was conducted to know the prevalence of alloimmunization in thalassemia patients, in the Caspian Sea coastline. Methods: This study is a descriptive, retrospective analysis of transfusion records of 190 patients with β-thalassemia major who received regular transfusions. To detect the type of alloantibodies, two cells panel tests (kits; Iranian Blood Transfusion Organization [IBTO], 3 RBC cells and IBTO, 11 RBC cells) were used. Results: Forty-seven patients were positive for alloantibodies (24.7%). Of them, 18.4% (35 cases) had only one alloantibody, and 6.3% (12 cases) had at least two or more of alloantibodies. The vast majority of alloantibodies were anti-Kell followed by anti-E, and anti-D, respectively. Conclusions: Blood matching for Rh and K antigens in patients with transfusion-dependent thalassemia could reduce the rate of RBC alloinununization.