In order to ascertain whether PVA fibers can produce cancer in humans or not, we have conducted a retrospective cohort study of workers exposed to PVA fibers. A total of 447 exposed and 2416 non-exposed male workers who were engaged before 1980 were followed up until the end of 1996. The SMR for all causes was 0.57 (observed 38, 95% CI: 0.41-0.78) for the exposed, and 0.66 (observed 210, 95% CI: 0.58-0.75). As for lung cancer, its SMR was 0.77 (observed 3, 95% CI: 0.15-2.24) for the exposed workers and 0.67 (12 observed, 95% CI: 0.34-1.16) for the non-exposed workers. Lung cancer SMR was 0.86 (observed 2, 95% CI: 0.10-3.11) for the workers with 20 or more years' employment. This study showed no difference in lung cancer risk between the workers exposed to PVA fibers and the non-exposed workers.