Abstract : We have investigated the role of the occupation and of occupational exposures to petroleum and chlorinated solvents using the data of two epidemiological studies on occupational risk factors of breast cancers in men and in women. Unlike female breast cancer (50,000 new cases per year inFrance), cancer of male breast cancer is a rare disease (<500 cases per year). It should be seen as an interesting model for studying the effects of occupational exposures in the disease as these exposure are generally much higher in men than in women. For men, our results suggest that the risk of cancer is increased among motor vehicle mechanics and support the hypothesis of a carcinogenic effect of solvents such as benzene and trichloroethylene in disease occurrence. In women, several occupations were at increased risk of breast cancer, but results were generally not statistically significant. No association of female breast cancer incidence with exposure to solvents was observed.