Both in France and in Italy hepatitis B is present mostly among the migrant population coming from sub-Saharan Africa and mainly among those migrants having a poor socio-economic background. This article is aimed at assaying the impact of public policies adopted by France and Italy for migrants' health on the treatment of migrants with HBV. The article is based on semi-structured interviews conducted with 30 immigrant adults taken into care by two associations dealing with medical, psychological and social issues of immigrants applying for a residence permit, mainly asylum seekers. The results of this study bring to light specific difficulties relating to national contexts, to the type of HBV (inactive or active) and to the administrative situation of the migrants. In France irregular migrants are screened in humanitarian associations. In Italy the screening is done in public hospitals. In both countries, only migrants suffering from chronic hepatitis B obtain a residence permit for medical reasons. More migrants in Italy than in France abandon HBV treatment. This study describes how specific national immigration and health policies impact in a different way the therapeutic and social path of migrants suffering from hepatitis B. The analysis provides useful material for the development of strategies to prevent and control hepatitis B among the migrant population. It also shows how social determinants affect migrants' health more than values or cultural factors do.