The class of aryl sulfonamides was studied in order to nominate chemicals to the Chemical Selection Working Group as candidates for carcinogenesis bioassay. After application of several qualifying criteria relating to previous, current, or planned carcinogenicity tests and to commercial significance, the preliminary candidate list of 189 chemicals was reduced to a list of 89 chemicals. Based upon consideration of both the suspicion of possible carcinogenic activity and evidence indicating potential exposure, the following five chemicals were nominated: sulfanilamide, sulfamethazine, sulfathiazole, sulfamethizole, and salicylazosulfapyridine.