Of 253 prospectively studied cases of acute viral hepatitis (AVH), 47 were fulminant (18.6%). There were 15 males and 32 females. Their age ranged from 7 to 60 years (mean, 28 years). Serological evidence of AVH-A was found in one case (2%), AVH-B in 13 cases (28%), AVH-D in one case (2%), and AVH-NANB in 32 cases (68%). Fulminant hepatitis was found in 2.6% of AVH-A cases, in 16.25% of AVH-B cases, in one of two AVH-D superinfections, and in 24.8% of the AVH-non-A, non-B (NANB) cases. The clinical picture in the two main etiological categories, namely the AVH-B and the AVH-NANB, showed that the latter possessed a more prolonged and severe clinical course with higher mortality (P <0.001). It also showed a higher mortality in females of the child bearing age, compared with males of the same age group (P <0.001).