The Rh system is a clinically important blood group be- cause it induces Rh negative incompatible blood transfu- sion, and hemolytic disease of the newborn. The most immunogenic and clinically important antigen is D (RH:01;RHD01allele) because D antigens consist of at least 30 epitopes. The RHD negative phenotype results from a homozygosity for a deletion of the wholeRHDgene in the Caucasian. In Africans, it can result in gene deletion the presence of the pseudogene (RHD04N.01)–aRHD gene with a 37 pb insertion of the last 19 nucleotides of in- tron 3 and the first 18 nucleotides of the exon 4, which may introduce a reading-frame shift and premature stop codon, plus a nonsense mutation in exon 6, and a hy- brid geneRHD-CE-Ds. In the Japanese, the presence of theRHDgene in D negative individuals was detected, and the ratio of theRHDgene in Japanese D nega- tives was estimated to be 12.5%, which was higher than expected. In Brazilian Japanese descendants the fre- quencies ofRHDgenes were in accordance to that observed in the population from Japan.