Mortality records from 24 states, gathered from 1984 to 1989 and coded for occupation and industry, were used to develop leads to workplace exposures as possible breast cancer risk factors. A case-control approach was used, with separate analyses for blacks and whites. After excluding homemakers, 33,509 cases and 117,794 controls remained. A job exposure matrix was used to estimate the probability and level of 31 workplace exposures. After adjusting for socioeconomic status, suggestive associations for probability and level of exposure were found for styrene, several organic solvents (methylene chloride, carbon tetrachloride, formaldehyde), and several metals/metal oxides and acid mists. Because of the methodologic limitations of this study, its primary value is in suggesting hypotheses for further evaluation. The findings for styrene, selected solvents, and metals and metal-related exposures deserve additional study.