An unusual cause of fulminant hepatic failure is described. The patient, who presented with symptoms of liver disease, proved to have a small primary oat cell carcinoma of the lung with massive hepatic metastases. The clinical evolution was rapid, with marked elevations of SGOT (this without a prior hypotensive episode) and hepatic coma. Examination of the liver showed two types of necrosis: 1. infarction secondary to multiple tumor emboli in portal vessels and 2. overrunning of hepatic cell plates by expanding masses of tumor cells (somewhat analogous to piecemeal necrosis).