Abstract: The Rh blood group system is the most complex, polymorphic and immunogenic protein-based blood group system in humans. Some individuals produce a weak expression of D antigen on RBCs surface as a result of missense RHD mutations and amino acid substitutions that lead to distinct serologic phenotypes and anti-D immunization. This study aimed to elucidate the molecular genetic basis of weak D phenotypes in Malaysian blood donors with multiracial population. A total of 183 Rh-negative blood samples were phenotyped for D, C, c, E and e antigens. Weak D samples that identified by Indirect Antiglobulin Test (IAT) were amplified by polymerase chain reaction-sequence specific primers for weak D type determination. A total of 183 multiracial Rh-negative donors were reviewed, consisting of 88 (48.1%) Indians, 56 (30.6%) Malays, 23 (12.6%) Chinese and 16 (8.7%) other minority ethnics. Four samples were found to be positive for weak D phenotype using IAT. Of these four samples, two samples were reported with weak D type 15. Both samples were from Chinese blood donor with DweakCcee and DweakccEe phenotype, respectively. This study provide the first database of a molecular basis of weak D in Malaysian blood donors which improved the understanding of molecular mechanisms underlying D antigen expression in Malaysian population. Thus, increase the transfusion safety in highly racial mixed population.