The study presented was aimed at a comparative evaluation of nutrition of seamen working on board ocean-going vessels. Evaluation of the nutritive value of daily menus showed the mean energetic value to substantially exceed recommended daily allowances. The proportion of protein- and fat-derived energy in the daily menus turned out to be too high, while the contribution of energy derived from carbohydrates was too low. In spite of significant between-ships differences in protein and fat consumption, the overall protein and fat consumption by all the seamen exceeded the recommended daily allowance by at least 100 and 160-200%, respectively. The excessive consumption of protein and fat resulted in a relative deficiency of carbohydrates. Although the absolute amounts consumed met the nutritional requirements, the carbohydrate-derived energy provided as little as 46-49% of the total energy intake. On the other hand, the dietary fibre uptake (51.2±6.8 and 35.4±5.9 g) was high. The analysed menus the quantitative and qualitative composition of which is regulated (Polish Steamship Company Director General´s Regulation No. 17 of 10 July 1998) were found to significantly differ in the amounts of basic diet components. The diets were, however, comparable in terms of their vitamin contents which greatly exceeded the recommended daily allowances. The fluid intake was appropriate. The results obtained allow to conclude that the regulations pertaining to quantitative and qualitative composition of daily menus on board the Polish Steamship Company ships should be revised. It would be advantageous to provide more nutrition-centred education to the seamen, because the diets offered on board frequently depend on their wishes and no change is possible without their approval.