Summary. Hepatitis B virus infection (HBV) has been recognized as a major health problem worldwide. Greece belongs to the intermediate endemicity countries with a trend of decreasing prevalence of HBV infection during the last decade. However, the recent massive immigration to our country may have led to alterations of HBV epidemiology. In this study, we evaluated the epidemiological features of HBV infection in a sample of 3480 patients followed up during the years 1997–2006. Immigrants mainly from Albania represented the 18.6% of the total study population and 56.6% of children. The majority of the patients had no family history of HBV infection (67.3%) or of acute hepatitis (95.4%), no known source of infection (64.6%), with intrafamilial spread accounting for 16.9% of the HBV transmission in adults and 33.9% in children. HBeAg(-) hepatitis B was the predominant form of hepatitis (92.1%) among the Greek patients in contrast to the immigrants where 16.6% were HBeAg(+). Liver cirrhosis was diagnosed in 8.8% of the total population and 0.9% had hepatocellular carcinoma. A high proportion of children were HBeAg(+) (62%), 55% from immigrant families, 25.2% were infected in the perinatal period and had no evidence of disease complications. In conclusion our results showed (a) a changing pattern in the epidemiology of HBV infection in Greece due to the significant number of HBeAg(+) patients, especially among children and (b) a considerable number of patients although aware of their infection, present with advanced disease.