
The ABO and Rh blood groups are the most important blood group systems in humans with tremendous variability among different races and ethnic groups. Their clinical importance is evident in blood transfusion and hemolytic disease of the newborn. A number of associations have been reported between diseases and blood group systems. This study aimed to determine the frequencies of Rhesus blood group phenotypes and probable genotypes of major Sudanese tribes. Following informed consent, one thousand venous blood samples were collected from unrelated individuals from ten Sudanese tribes. Red blood cells were tested for common Rhesus antigens suing Particle gel immune diffusion and slide agglutination techniques. The phenotypes, haplotypes and most probable genotypes were determined. Similarities between different Sudanese populations were calculated using Jaccard’s coefficient of similarities. Phenotypic data obtained was referred to as alleles, haplotypes, genotypes based on reasonable assumptions that every Rh blood group antigen represents a gene that is always expressed and has a Mendelian dominant mode of inheritance. The ē, and D were the most common antigens/alleles with frequencies of 98.4%, 93.8% and 90.7% respectively. The C and the E antigens/alleles were less frequent. The most prevalent haplotype complex was / (frequency= 44.2%) and the least common was the / (frequency= 0.1%).The most prevalent genotype was with a frequency of 44.2%, while and genotypes were detected with lower frequencies of 21.7% and 10.9% respectively. The , , CdE and C E genotypes were the least common. In conclusion, ē, and the D antigens/alleles were the most common among the major Sudanese tribes. The C and the E antigens were the least expressed. The Commonest Rh haplotype/genotype encountered was the .