Habitual heterosexual contacts of chronic HBV infection carriers show high prevalence of infection markers that does not result to be sex related, and results significantly associated to increase of age, presumably as a consequence of duration of exposure. Concomitance of habitual sexual contacts does not represent in an infected family setting a risk factor of higher prevalence of HBV infection, in respect of multitude of occurrences of unperceivable expositions to contagion.