Epidemiological data obtained to date show that the delta agent is spread all over the world. In Rumania hepatitis B virus infection is widespread and is associated with a high incidence of chronic liver disease. To determine the prevalence of delta infection, sera from 373 patients with chronic liver disease were tested for HBV markers; 228 were HBsAg positive. Anti-HD was present in 190 sera (83.33%), which reveals a very high incidence and shows a higher frequency of the active forms of the disease. However, in contrast to other studies, we found a high incidence of HDV infection in chronic persistent hepatitis and hepatocellular carcinoma.