A total of 2,208 male subjects, enrolled as merchant marine seamen at the Civitavecchia (Italy) harbor from 1936 to 1975 were followed up through 1989 in order to evaluate their mortality experience. Available information about the number of sailings made it possible to divide subjects into two subgroups: 948 workers with at least one sailing (cohort A) and 1,260 with no reported sailing (cohort B). Fewer than expected overall deaths were observed in both cohorts (cohort A: SMR = 0.83; cohort B: SMR = 0.81), mainly due to a lower mortality from circulatory, respiratory, and digestive diseases. Lung cancer deaths were significantly increased in cohort A (O = 30, SMR = 1.71, 95% CI = 1.15-2.44), whereas no excess was observed in cohort B (O = 6, SMR = 0.57, 95% CI = 0.21-1.26). Among subjects employed aboard ship, a trend in SMRs for lung cancer increasing with duration of employment was observed. Furthermore, three neoplasms of other parts of the respiratory system (including one mesothelioma) were detected in cohort A (SMR = 5.87), and one in cohort B. The study substantiates an increased risk of respiratory cancer among subjects with an occupational history of sailing; past exposure to asbestos and to other environmental carcinogens aboard could be implicated.