Haemolytic Disease of Foetus and Newborn (HDFN) and Haemolytic Transfusion Reaction (HTR) may occur due to antibodies against Kidd antigen. In Malaysia, the prevalence of RBC alloimmunization due to Kidd antibody for cases of HDFN and HTR have been reported [1-2] however there is insufficient data in Hospital Umum Sarawak (HUS).The aim of this study is to determine whether Kidd alloimmunization causes HDFN and HTR. Indirectly categorize Kidd phenotype blood in regular blood donors.