De novo hepatitis B virus (HBV) infection after orthotopic liver transplantation (OLT) in patients negative for hepatitis B surface antigen (HBsAg) is between 1.7% and 3.5% in areas with a low prevalence of HBV infection. The importance of this problem and the efficacy of lamivudine treatment has not been defined in areas with a high prevalence of positivity to antibody to hepatitis B core antigen (Anti-HBc). To define the characteristics and the clinical impact of de novo HBV infection in OLT recipients and to evaluate the efficacy of lamivudine treatment in this context, 229 HBsAg (-) donors (145 men, 84 women) were retrospectively evaluated between June 1994 and June 2000. Forty-eight recipients were excluded for various reasons. The final study population included 181 patients that were prospectively followed up for more than 6 months after OLT. When de novo HBV infection was detected, liver allograft biopsy was performed and treatment with lamivudine was indicated if patients were HBV-DNA-positive with elevated ALT levels. Survival time was defined as the interval between diagnosis of HBV infection and death or last follow-up visit. Thirty-one of 229 liver donors (13.5%) were anti-HBc(+). After a mean follow-up of 54.4+/-30 months, 9 of the 181 recipients (5%) developed de novo HBV infection; 8 of 27 recipients (29.6%) of livers from anti-HBc(+) donors as compared with only one of 154 recipients (0.6%) of livers from anti-HBc(-) donors P < 0.005). Liver biopsies performed in 8 of 9 cases showed chronic active hepatitis in 7 patients and acute hepatitis in one patient who cleared HBV spontaneously during the first 3 months. Seven patients were treated with lamivudine for a mean period of 24.5 months; HBV-DNA became negative in 5 of 7 (71.4%), and HBeAg became undetectable in 3 of 6 patients (50%). Patient actuarial survival rates at 1, 3, and 5 years were 100%, 94.7%, and 81.2% for recipients of anti-HBc (+) livers and 95.2%, 83%, and 77.3% for recipients of anti-HBc (-) livers P = ns). In our area, the appearance of de novo HBV infection after OLT is related to grafting livers from anti-HBc (+) donors is associated with a benign outcome, with no liver failure or graft loss, and treatment with lamivudine is highly effective in the control of HBV replication.