To evaluate exposure to hepatitis B virus (HBV) in dental operators, we surveyed 297 students of the Dental School, University of Milano, and 526 dentists registered at the Italian Dental Association (A.M.D.I.) of Lombardia. Out of 297 students, 10.8% had one or more serologic markers of HBV infection; none was hepatitis B surface antigen (HBsAg) positive. No significant difference in seropositivity was detected among students in relation to sex, age, or possible risk factors investigated. Out of 526 practitioners, 2.3% were positive for HBsAg, and 37.3% were antibody positive. The seropositivity increased progressively with age and years of professional experience, reaching the highest proportion in dentists with 30 years or more of practice (79.3%). Of those who had suffered from clinical hepatitis during their curriculum, 81.1% were seropositive compared with 34.5% observed in dentists without a prior clinical history of viral hepatitis. The proportion of seropositive dentists did not vary significantly with a history of blood transfusion, size of their practice, presence or absence (or unawareness) of subjects at high risk for HBV infection among their patients. The seropositivity was significantly lower in dentists who routinely adopted mask and gloves (21.1%) compared with those who never and/or occasionally used such barriers (46.3%). The result of the study confirmed that hepatitis B does remain a significant hazard for dental professionals, hence immunization with hepatitis B vaccine should be delivered early in their employment.