HLA allele and haplotype frequencies are used in transplantation, anthropology, forensic medicine, and studies of the associations between HLA factors and the immune response. The cost of determining these frequencies through family studies can be avoided by estimating them from population data. We have utilized the data in the UNOS donor registry and kidney transplant waiting list to estimate allele and haplotype frequencies for the HLA-A, -B, and -DR(B1) loci and report the allele and a portion of the haplotype data here. Using programs written in A Program Language (APL) we were able to perform all analyses on a personal computer. We have found that the distribution of haplotype frequencies varies among the races, with Caucasians having a greater number of both more common and extremely rare haplotypes. Despite the sizes of the groups studied, only one-third to two-thirds of the haplotypes theoretically possible were actually observed. Although the data confirm the well-known fact that the distributions of alleles and haplotypes varies among races, they also reveal that certain common haplotypes are shared among all racial groups and represent an opportunity for well-matched transplants between donors and recipients of different races.