131 cases of epidemic hepatitis from two villages in Xinjiang, were admitted to the provisional infectious diseases hospital from February to April 1987. In 125 (95%) patients neither anti-HAV IgM nor anti-HBc IgM were positive. 118 (90%) were drinking water from a local stream of the Hotan River. The study was conducted on 125 patients aged from 5 to 90 years, with a mean of 26.4 years. There were slightly more males than females, a ratio of 1.5 to 1. The incubation period was roughly estimated to be 17 to 37 days (mean 24.8 days). All subjects were jaundiced. 12 patients (including 6 pregnant women) had cholestatic symptoms. Except one woman who died of postpartum bleeding, all patients ran a benign course without fulminant hepatic failure. Pathologic changes of liver biopsies from 35 cases included lobular damage and inflammation, ballooned hepatocytes with clear cytoplasm and delineated cell membrane which were named "clear cell". There were cholestasis of different degrees in the acute icteric stage and fatty changes in the convalescent stage. It was seen under the electron microscope that the livers of 8 cases had neither tubular structure nor sponge-like inclusions, but had nuclear changes including curled edge of nuclear membrane and nuclear heterochromatin condensed in masses. Liver biopsies were repeated in 7 cases followed up for 6-13 months, and hepatohistology was normal in 5. Of the other two cases there was one of each.