BACKGROUND: The continuing migration of individuals from geographic areas with high/medium endemicity has determined the arrival of new chronic hepatitis B virus (HBV) carriers in Italy. The magnitude of this phenomenon and clinical/virological features of HBsAg-positive migrants remain not very well defined. AIMS: To evaluate the proportion of HBsAg-positive immigrants enrolled in this multicenter Società Italiana di Malattie Infettive e Tropicali (SIMIT) cross-sectional study and to compare the characteristics of chronic hepatitis B infection in migrants to those of Italian carriers. METHODS: From February 1 to July 31 2008, anonymous data were obtained from all HBsAg-positive patients aged ≥ 18 years observed at 74 Italian centers of infectious diseases. RESULTS: Of the 3,760 HBsAg-positive subjects enrolled, 932 (24.8 %) were immigrants, with a prevalent distribution in central to northern Italy. The areas of origin were: Far East (37.1 %), Eastern Europe (35.4 %), Sub-Saharan Africa (17.5 %), North Africa (5.5 %), and 4.5 % from various other sites. Compared to Italian carriers, migrants were significantly younger (median age 34 vs. 52 years), predominantly female (57.5 vs. 31 %), and most often at first observation (incident cases 34.2 vs. 13.3 %). HBeAg-positives were more frequent among migrants (27.5 vs. 14 %). Genotype D, found in 87.8 % of Italian carriers, was present in only 40 % of migrants, who were more frequently inactive HBV carriers, with a lower prevalence of chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). Only 27.1 % of migrants received antiviral treatment compared to 50.3 % of Italians. CONCLUSIONS: Twenty-five percent of all HBV carriers examined at Italian centers was composed of immigrants with demographic, serological, and virological characteristics that differed from those of natives and appeared to have an inferior access to treatment.