Fifteen male workers exposed to vinyl chloride developed angiosarcoma of the liver. Thirteen died of disease and two are currently living for short periods after diagnosis. Their ages ranged from 36 to 58 years (average 47.5 years). Their exposure time ranged from 4 to 27.8 years (average 16.9 years). The most common presenting symptoms were fatigue, weight loss, and abdominal pain. Hepatomegaly followed by splenomegaly were the most common physical findings. Biochemical profiles yielded variable results and proved to be of little value in the detection or diagnosis. Of eight patients autopsied, distant organ involvement was present in two cases, duodenal involvement in one, and direct extension of tumor to adjacent organs or tissues in four additional ones. The remainder, diagnosed by open liver biopsy, revealed no tumor extension. The gross features of the tumors were hemorrhagic necrosis, cystic degeneration, fibrosis, and apparent multicentricity. The histologic features were those of the typical angiosarcoma found in a variety of sites with a wide range of cellular differentiation. The histologic diagnosis was often impaired by the extensive tumor necrosis. Elsewhere in the liver subcapsular fibrosis, a distinct type of portal fibrosis, and endothelial cell hyperplasia with or without sinusoidal dilatation were noted. The reduction of industrial chemical exposure has already been achieved and will hopefully eliminate this chemically related tumor in the future. There is, however, a significant group of previously exposed workers who will require careful monitoring to detect functional abnormalities of the liver and possible early neoplastic changes.