The effect of prostaglandins (PG) in patients with fulminant and subfulminant viral hepatitis was studied. Seventeen patients presented with FHF secondary to hepatitis A (N = 3), hepatitis B (N = 6) and non-A, non-B (NANB) hepatitis (N = 8). Fourteen of the 17 patients had stage III or IV hepatic encephalopathy (HE). At presentation, the mean AST was 1844 +/- 1246 units/liter, bilirubin 232 +/- 135 mumol/liter, PT 34 +/- 18 and PTT 73 +/- 26 sec, and coagulation factors V and VII were 8 +/- 4 and 9 +/- 51%, respectively. Twelve of 17 patients responded to PGE1 rapidly, with a decrease in AST from 1540 +/- 833 to 188 +/- 324 units/liter, a decrease in prothrombin time from 27 +/- 7 sec to 12 +/- 1 sec, PTT from 61 +/- 10 sec to 31 +/- 2 sec, and an increase in factor V from 9 +/- 4% to 69 +/- 18% and factor VII from 11 +/- 5% to 71 +/- 20%. Five responders with NANB hepatitis relapsed upon discontinuation of therapy, with recurrence of HE and increases in AST and PT but improvement was observed upon retreatment. After four weeks of intravenous therapy, oral PGE2 was substituted. Two patients have recovered completely and remain in remission six and 12 months following cessation of therapy. Two additional patients continue in remission after two and six months of PGE2. No relapses have been seen in patients with hepatitis A virus (HAV) or hepatitis B virus (HBV) infection. Liver biopsies in the 12 surviving patients have returned to normal. These results suggest efficacy of PGE for FHF. Further investigation is warranted.