The clinical and laboratory data of 116 cases of severe hepatitis were evaluated by stepwise regression analysis, and the prognostic multiple regression discriminant equation of adult severe hepatitis was obtained. The formula is Y=0.0081X2+0.3039X3-0.2902X6-0.0219X9+0.1851X10+0.1628X12+0.2187X13+ 0.2403X14+0.3364X15-0.4619. It was found that the discriminant correspondence rate was 97.4% in retrospective evaluation. In prospective test for 53 cases of severe hepatitis the discriminant correspondence rate was 81%. The quantitative evaluation of prognosis in severe hepatitis is also discussed.