Individual phenotypes with respect to drug response or toxicity often result from genetic variations that alter drug metabolism. We have been focusing on genomic loci that encode various enzymes and transporters involved in the metabolism of drugs, and have described more than 1200 single-nucleotide polymorphisms (SNPs) and other variations. Regarding the carbohydrate sulfotransferase (CHST) gene family, we have already constructed high-density SNP maps of three genomic segments that included CHST2, CHST4, and CHST5, providing a total of 28 SNPs for those loci. In the present study, we screened DNA from 48 healthy Japanese volunteers for SNPs at the CHST1 and CHST3 gene loci, by means of direct sequencing combined with a polymerase chain reaction method for amplifying genomic DNA, and characterized 77 SNPs and four insertion-deletion polymorphisms. The collection of human variations presented here adds to the archive of tools now available for investigating complex genetic diseases, population migration patterns, and a variety of pharmacogenetic possibilities.