A 30-yr historical cohort mortality study was made of 264 men hired during 1935-45, who worked in a chrysotile asbestos products factor for 1 yr or more and were alive Jan. 1, 1945. Follow-up was 94% complete. The overall standardized mortality ratio (SMR) was only 0.61, while the SMR for all cancers was 0.75, for lung cancer 0.93 and for gastrointestinal cancer 1.05. Two men died of asbestosis. The overall SMR was higher for men who worked 5 yr or more than for men who worked 1-4 yr, but the 30-yr mortality rates were the same after age adjustment. For asbestos-related diseases the differences in work duration had no effect on mortality. The data show a favorable mortality experience for men exposed to chrysotile alone.