The proposed research will establish a cohort of workers exposed occupationally in the past to textile dyes derived from benzidine, o-tolidine, and/or o-dianisidine, and/or to textile finishes containing formaldehyde. Prospective observation of their full mortality experience from the time of first exposure, will be conducted. Expected and observed rates of death by cause will be tabulated to ascertain if unusual mortality patterns exist. Such data will have importance in assessing the human carcinogenicity of dyes derived from the above substances and of finishes containing formaldehyde.