The mortality and disability of cotton mill workers were studied in five Finnish cotton mills. The population under study comprised all 1065 women exposed to raw cotton dust who had been hired between 1950 and 1971. The minimum exposure period was five years. For the study on disability, the cohort was followed up until the end of 1981. The follow up period for the mortality analysis was from 1950 to 1985. At the end of 1981 the observed number of prevalent disability pensions for respiratory disease was 15, whereas 3.9 were expected (p less than 0.01) on the basis of the national figures for women. There were 46 musculoskeletal diseases (27.7 expected, p less than 0.01), of which 24 were osteoarthritis (14.5 expected) and 13 rheumatoid arthritis (6.6 expected). The incidence rates of disability pensions were calculated for the period 1969-81. Comparison of incidence rates between cotton mill workers and the Finnish female population showed excessive rates for both respiratory diseases (p less than 0.001) and musculoskeletal diseases (p less than 0.01), with an excess of new cases of rheumatoid arthritis (p less than 0.05). By the end of 1985 the number of person-years was 31,678 and the number of deaths 95. The standardised mortality ratios for the total period of follow up (1950-85) showed no excess for respiratory diseases. Mortality from cardiovascular diseases was also lower than expected. The observed number of tumours was 33, the corresponding expected number 32.0. Thirteen tumours were in the digestive organs (6.6 expected, p<0.05) and three were lung cancers (1.9 expected). Five workers had died from renal disease; the expected number was 1.5 (p<0.05).