In a cohort study of 5464 union organised Swedish chimney sweeps employed at any time between 1918 and 1980 mortality was studied from 1951 to 1982 with national statistics used as a reference. Follow up was possible for 98.6% of the individuals: 717 deaths were observed against 540 expected. There was an increased mortality from coronary heart disease, respiratory diseases, and several types of malignant tumours. Lung cancer mortality was significantly increased and positively correlated to the number of years employed. A fivefold risk increase for oesophageal cancer and liver cancer was found. The increased mortality could be attributed to exposure to combustion products in the work environment but not to smoking habits.