The course of vinyl chloride-induced disease observed in 21 polyvinyl chloride (PVC) production workers, covering the period from first exposure to diagnosis and finally to death, and the difficulties in elucidating the true character of the lesions and their occupational origin are described. In 19 cases death was due to malignant hepatoma, predominantly angiosarcoma of the liver, but hepatocellular and cholangiocellular carcinoma were also found. Two workers died of complications of noncirrhotic portal fibrosis with portal hypertension. Except for the final stages, there was strikingly little impairment of hepatic function. Latency periods in workers with malignant hepatoma ranged from 12 to 34 years; mean latency was 22 years, and younger age at first exposure (here age < 27) seemed to have been accompanied by shorter latency periods.