Seroepidemiologic study on hepatitis B virus markers in a group of students in Medicine at the University of Brescia. The prevalence of hepatitis B virus (HBV) markers was studied in a group of 633 students in Medicine at the University of Brescia. HBsAg was detected in 16 (2.5%) students; anti-HBs and anti-HBc in 73 (11.5%); anti-HBs alone in 4 (0.6%); anti-HBc alone in 9 (1.4%). On the whole 102 (16.1%) students were reactive for one HBV marker at least. Significant differences in frequency of HBV markers were found according to age and to personal and familiar history of viral hepatitis; the prevalence of the markers was not associated with sex, year in school, hospital clinical training, blood transfusions and presence of health-care workers in the family. In this seroepidemiologic study the risk of contracting hepatitis B appears not higher in medical students than in other university students and in general population of the same age, sex and residence area. The results of the investigation suggest that medical students are appropriate candidates for hepatitis B vaccine at the beginning of their post-graduate medical profession.