In the framework of the campaign for anti-HBV vaccination conducted by the Regione Piemonte, the Mauriziano Hospital in Valenza and the Unità Sanitaria Locale 71, screened and then vaccinated a group of 199 medical workers at risk of HBV. It was found that the infection was asymptomatic in the vaccinated subjects (16%) and the chronic HBsAg carriers (1.5%), that the risk of infection increases with age (p less than 0.01) and length of service (p less than 0.05) and that there is a connection with the mean figures produced by other studies conducted on hospital staff. Vaccination gave satisfactory results, with protective antibody responses in 87% of the cases, of whom about half presented levels over 1000 mIU/ml and no significant side effects.