Hyporesponsiveness (anti-HBs 10-100 IU/l) or non-responsiveness (anti-HBs < 10 IU/l) to hepatitis B vaccines is a problem in approximately 20-70% of HIV-positive patients. Mechanisms for impaired humoral and cellular immunity related to the HIV infection are reviewed. Contributing risk factors like age, gender, CD4+ T-cell count, HIV RNA load and coinfection with hepatitis C are highlighted. New developments in improving the HBV vaccine immunogenicity are discussed and clinical recommendations are given for HBV-re-vaccination of HIV patients who failed on standard HBV vaccination.