Background: The safety of life and work at sea depends, among other things, on the state of health of the members of the crew. Despite preliminary fitness selection, death at sea is still frequent. In the present paper, causes and circumstances of fatal cases at sea in the years 1985-1994 were analyzed for one Polish shipping company. Methods: Analysis was based on medical documentation and reports of accidents prepared by health centers, the employer and the marine judiciary. The effects of work conditions, as well as disease, on the resulting death were taken into account. The data obtained were compared to the mortality in nonseafaring men of productive age. Results: The most frequent causes of deaths were sea catastrophes, circulatory system diseases, injuries, and poisonings (a total of 85%). Next were suicides, "missings," and cerebral apoplexies. Seamen of 50 to 59 years of age died most often, primarily of myocardial infarction. Fatal events occurred in different places (mostly at sea, less frequently in port). Certain onboard occupations were identified as most dangerous for fatal accidents. The shipowner acknowledged 60% of the deaths as accidents at work. The effects of weather conditions, stress, overstrain, and lack of access to qualified medical assistance were analyzed. A relationship between diagnosed disease and death was found only in the case of myocardial infarction and cerebral apoplexy. In scarcely 15% of these cases were preliminary symptoms noticed, while behavioral and personality disturbances were earlier observed in the majority of suicides. Conclusions: The ship has remained one of the most dangerous workplaces, and fatal cases are to a large extent related to specific labor conditions at sea.