The possible hazard of lung cancer among cooks was studied in a cohort of 1798 cooks who had retired from the Army Catering Corps and 1310 referents retired from the Royal Army Pay Corps. During the follow-up from 1974 to 1989 the mortality of the referents was similar to that of the national population, apart from a moderate increase in lung cancer [standardized mortality ratio (SMR) 1.38]. Mortality from lung cancer among the cooks was significantly higher than among the national population [SMR 1.82, 95% confidence interval (95% CI) 1.25-2.57], as was mortality from cancer of the large intestine (SMR 3.03), ischemic heart disease (SMR 1.42), cerebrovascular disease (SMR 2.05), and digestive disease (SMR 2.27). The high rate of lung cancer among the cooks supports the hypothesis of an occupational hazard, although at least part of the excess was probably due to smoking. Possible explanations for the elevated mortality from other diseases include poor nutrition in early life, smoking, and high consumption of alcohol.