More than half of the recognized carcinogens are from occupational origin and in France about 2 million of workers are exposed. Almost every site of cancer may be involved, the lung being the most frequent organ followed by the bladder, the skin, leukemia, the nose, the liver and the larynx. While several thousands of cases occur each year in France, only 15 to 30% are compensated. Occupational exposure contributes largely to the social inequalities in cancer incidence and mortality. However, occupational cancer could be largely prevented through the elimination of the most toxic occupational exposures and the control of exposure levels.