Alloimmunization to erythrocyte antigens, of variable clinical significance, is afrequent finding in thalassemic multitransfused patients. The rate of such antibodies is29.6% in our study.Such antibodies are usually responsible for delayed hemolytictransfusion reaction, with the resulting destruction of the transfused red cells.The aim of this work was to screen for alloantibodies against red cell antigens and toidentify these antibodies using ID Microtyping System.Our study included 172 thalassemic multitransfused patients,they were 84 males and 88females.The patients were subjected to the following investigations : ABO grouping and Rh detection, Screening of the patient's plasma/serum for antibody presence byinducing a reaction between antibodies in patient's plasma/serumand blood group O cells of known phenotype(SURGISCREEN 1, 2 and 3), Antibody identification of patients with positive screening or change inparameters of the new screening from the previous one to detect thedevelopment of new alloantibodies&the type of these antibodies usingRESOLVE®panel A and B. 51 patients of the 172 patients gave positive results and showed antibodiesagainst the different red cell antigens,with the percentage of alloimmunization to redcell antigens 29.6%.The antibodies to Rh system antigens and to Kell antigen weredetected most frequently which reflects the greater immunogenicity of these red cellantigens. According to these results,current guidelines for matching by ABO,Rh andKell systems compared to blood phenotypically matched for the standerd ABO-D is tobe effective in preventing alloimmunization in patients with thalassemia.