We performed this research in other to describe this situation in multiply transfused Thalassemic patients at Children's Hospital 1.Methods - Objective: This study included 121 thalassemic patients having usual transfusions more than 3 times with ABO and Rh (D) compatible blood or whole blood cells at Children's Hospital 1, in Ho Chi Minh city, from 1st April 2008 to 31st September 2008.Results: The result showed that: the rate of the red cell alloimmunization was 24.8%.