This cohort study investigated mortality patterns in Danish commercial fishermen between 1970 and 1985, compared to all economically active men. The population census in 1970 in Denmark was the source of information on individual occupation, age and economic status. Computerised linkage with the Danish Mortality Register gave information about deceased persons' date and cause of death. Standarised mortality ratio (SMR) for all causes among crew members was 1.50; 95% confidence intervals (95% CI) 1.34-1.65) highest in the age group 20-34 years (SMR = 2.09, 95% CI 1.68-2.58). The increased SMR among fishermen was primarity due to deaths by accident other than road accidents (SMR = 5.76, 95% CI = 3.09-7.46), ischemic heart disease (SMR = 1.27, 95% CI, 1.01-1.57) and causes without information (SMR = 6.44 95% CI 4.31-9.27). SMR due to bronchitis and emphysema among 35-64 years old crew members was 1.96, 95% CI 1.01-3.45. Among skippers, the SMR for all causes was 1.12, 95% CI 1.03-1.20). The study confirms earlier findings of a high mortality among fishermen, especially due to accidents, and a slightly increased risk of dying from cancer, respiratory and cardiovascular diseases.