Commonly quoted ABO/Rh(D) frequencies in the US are usually from relatively small studies with racial or ethnic categories often judged by name or appearance. A 10-year demographic database that contained racial or ethnic and ABO/Rh(D) phenotype data on 3.1 million allogeneic and autologous donors giving blood at five blood centers in the US was used to compute ABO and Rh(D) phenotypes in various racial/ethnic groups. The racial or ethnic category was designated by the donor. The highest percentage of Group O was found in Hispanic (56.5%), North American Indian (54.6%), and black non-Hispanic (50.2%) donors. Hispanic and black non-Hispanic donors had a much lower percentage (7.3 and 7.1%, respectively) of Rh- compared to white non-Hispanic donors (17.3%). Group O Rh- and Group B Rh- were found more commonly (8.0 and 1.8%, respectively) in white non-Hispanic donors than in Hispanic (3.9 and 0.7%), black non-Hispanic (3.6 and 1.3%), and Asian (0.7 and 0.4%) donors. These data confirmed that the highest percentages of ORh+, BRh+/ABRh+, and Rh- are present in Hispanic, Asian, and white non-Hispanic donors, respectively. These are the largest and most accurate data of ABO/Rh(D) phenotype frequencies for the major racial/ethnic donor groups in the US.