Background/Aims: In HIV-infected patients, who have recovered completely from an acute hepatitis B infection and become anti-HBs positive, hepatitis B infection may be reactivated after progression to AIDS, Case Report: We present the case of a homosexual male patient with AIDS who developed clinical and serological reactivation of hepatitis B with detectable HBV-DNA 18 years after complete recovery from acute hepatitis B infection, Prior to reactivation, antiretroviral triple therapy including lamivudine was changed to therapy without lamivudine. After reintroduction of lamivudine in the triple therapy HBV-DNA became undetectable and the patient lost HBsAg and again developed anti-HBs antibodies. Conclusion: The hepatitis B in this patient can be explained best by reactivation of persistent HBV infection, possibly because of transient decline in antibodies against HBs-antigen due to a reduction in CD4+ lymphocyte numbers and B cell dysfunction, This observation points to the clinical relevance of HBV persistence in serum and blood cells of anti-HBs-positive subjects for many years after recovery from acute hepatitis B infection, The possible role of lamivudine withdrawal which immediately preceded HBV breakthrough in our patient is noteworthy. Regular monitoring of markers of HBV infection, including HBV-DNA, in patients with AIDS appears justified after discontinuation of lamivudine.