A clinical and etiological study of 171 cases of acute hepatitis in subjects over 15 years of age showed that 73.7% were of the B type and 25.7% of the non-A, non-B type. A single case of hepatitis A was seen. Hepatitis B and non-A, non-B affect equally young men and women (mean age, 29 and 28, respectively), and infection occurs, for both types of hepatitis, by the parenteral route. More than 90% of cases recovered completely. The search for markers of hepatitis B virus in subjects with chronic liver diseases has shown that the B virus plays an important role in these diseases in Morocco: 6.7% of controls, 38.5% of cirrhotics and 40.9% of patients with chronic hepatitis were carriers of HBsAg. The anti-hepatitis Bc antibody was present in 53.3% of the control population, in 86.5% of cirrhotics and 90.9% of active chronic hepatitis patients. Hepatocellular carcinoma is relatively rare in Morocco, representing 5.9% of hepatic tumours and accounting for one hospitalization out of 84. It occurs in older subjects (mean age, 58 years) and more often in men than in women (40:23). The presence of HBsAg was investigated in 46 patients and 379 controls: it was found in 17% of hepatocellular carcinoma patients and 4.7% of controls. Anti-HBc antibodies were present in 76.8% of patients and 53.3% of controls.