Both prisoners and staff were tested in six correctional facilities. A total of 385 subjects, corresponding to a proportion ranging from 40 to 65 percent of the population of each facility, were studied (225 males and 48 females), and 255 attending personnel corresponding to 70 percent of the total employees were tested. From each consenting subject, blood was collected for HBV serum marker (HBsAg, antiHBs, antiHBe) detection and transaminase assay. Information was obtained on age, length of imprisonment or employment, history of liver disease, parenteral drug abuse, sexual habits, and exposure to parenteral HBV contamination (blood transfusions, major surgery, dental care, injections, and tattooing). The HBsAg carrier rate was 6.7 percent in inmates and 6.6 percent in staff. Sixty-five percent of the HBsAg-positive subjects were antiHBe-positive. When the blood samples were taken, all the HBsAg-positive subjects were asymptomatic; transaminases were normal in 80 percent and only slightly elevated in 20 percent. Illicit drug abuse was found to be a relevant risk factor for HBV infection among inmates under 35 years-old, but not in the older group; no correlation emerged between the presence of HBV serum markers and tattoos or admitted homosexuality. A high prevalence of HBV serum markers was found among young corrections officers who had been in service for a short time; most of them, however, came from areas of Italy with a particularly elevated HBV circulation. Tabular data and 13 references are provided.