One hundred dental surgeons practising in western France were immunized against hepatitis B virus, using the same batch of HEVAC B vaccine from the Pasteur Institute. The vaccine was very well tolerated. Seroconversion at 10 m IU/ml was 94% after 3 injections and 98% after the booster dose. From a kinetic study of anti-HBs antibodies we were able to determine different levels of post-immunization serological response and to classify responders as very good, good and fairly good. The effectiveness of the booster dose was manifest after 10 days. In view of the efficacy and safety of this vaccine, confirmed by other studies in sanitary personnel, we do not hesitate to recommend it to dental surgeons exposed to the disease.