The dockyards of Genoa are exposed to many known or suspect carcinogenic agents, namely, asbestos, silica, polycyclic aromatic hydrocarbons, and halogenated hydrocarbons; other possibly harmful substances are trace amounts of aromatic amines, welding smokes, paints, and lipid-removing solvents. A cohort study of causes of death of 2190 dockyard workers in Genoa was conducted between January 1, 1960 and December 31, 1975. Mortality rates were calculated for 20 different occupational categories, for which there exist different levels of exposure to noxious substances. Two control groups were selected: the general male population of Genoa and all male employees (462) of San Martino Hospital, Genoa for the same period of time. Causes of death that demonstrated significant excesses for both control groups were: cancer of the colon, excluding the rectum; cancer of the larynx; cancer of the lung, bronchus, and trachea; cancer of the kidney, urinary bladder, and other urinary organs; respiratory diseases; and cirrhosis of the liver. The data obtained from these 20 job categories revealed different types and levels of risk for various carcinogenic agents.