Studies with recombinant hepatitis B vaccines show seroprotection rates varying between 91 and 100%. Thus, a limited risk may remain for non-responding populations (e.g. non-responders, haemodialysis patients, elderly) who could benefit from a more immunogenic hepatitis B vaccine. One strategy to enhance the immune response is the use of novel adjuvants. SmithKline Beecham has developed a new adjuvant system containing alum and 3-deacylated monophosphoryl lipid A: SBAS4 (SmithKline Beecham Adjuvant System 4). Pilot studies showed that SBAS4 improved in vivo humoral and in vitro cellular immune responses compared to the response to classical recombinant hepatitis B vaccines and was safe and well-tolerated. Several studies assessed the profile of the HBsAg/SBAS4 vaccine in a healthy population, non-responders or elderly. In general the HBsAg/SBAS4 vaccine was well tolerated. Compared to an established recombinant hepatitis B vaccine, we observed an increased local reactogenicity but few symptoms were reported as severe. The HBsAg/SBAS4 vaccine elicits a strong immune response: subjects are protected faster and the GMTs are usually much higher. HBsAg/SBAS4 thus has the potential to protect those subjects who fail to be protected by well established hepatitis B vaccines.