An epidemiological mortality study will be undertaken to analyze the experience of a cohort of approximately 4,000 shipyard workers, characterized by trade, employed in a major eastern shipyard in 1967 for at least ten years and traced through 1980. Since many of these men began work (and asbestos exposure) 1940-1955, their experience will provide important information concerning the cancer risk associated with asbestos shipyard exposure. These data will provide information concerning two important questions: the extent and nature of asbestos-associated disease with low-level, intermittent, episodic asbestos exposure, an important problem in much of American industry, including construction and shipyard work. Second, there are now plus or minus 4,000,000 Americans currently (225,000) or formerly engaged in shipyard work at sometime 1940-1975. Available information indicates that this group is at high risk of developing cancer in the future. It is anticipated that the information in this investigation will assist in identifying criteria for the development of an optimum medical surveillance program, a matter of considerable practical importance.