AIMS: To describe cause specific mortality and site specific cancer morbidity among workers employed in factories that produce polyurethane foams, and to determine if any part of the experience may be caused by occupation, in particular to investigate any association between respiratory disease (malignant and non-malignant) and exposure to diisocyanates. METHODS: The mortality (1958-98) and cancer morbidity (1971-94) experienced by a cohort of 8288 male and female employees from 11 factories in England and Wales engaged in the manufacture of flexible polyurethane foams were investigated. All employees were employed for at least six months with some period of employment in the period 1958-79. Two analytical approaches were used, indirect standardisation and Poisson regression. RESULTS: Compared with the general population of England and Wales, mortality from lung cancer in female employees was significantly increased (observed (Obs) 35, expected (Exp) 19.4, standardised mortality ratio (SMR) 181). A similar excess was not found for male employees (Obs 134, Exp 125.0, SMR 107). There were no significantly increased cause specific SMRs among the subcohort (n = 1782) with some period of isocyanate exposed employment. No significant positive trends were found between risks of lung cancer or risks of non-malignant diseases of the respiratory system and durations of "lower" or "higher" exposures to diisocyanates. CONCLUSIONS: The study has been unable to link isocyanate exposed employment either with risks of lung cancer or with risks of non-malignant diseases of the respiratory system. The increased SMR for female lung cancer is most likely caused by factors unrelated to the industry under study.