The vaccinal status of adults is not well known but there are reasons to think it is fair from satisfactory. On the occasion of far away travels or premarital or antenatal special examinations, or systematically, every medical doctor should check his patients' state of immunization, regarding the main infectious hazards. Some situations need special attention: patients suffering from chronic visceral diseases, or elderly; people traveling to endemic countries (the case of diphtheria testifies to the development of new hazards all over the world); people with special leisure activities (such as hunting or fishing), or at risk behaviours (alcohol, tobacco, or some sexual practices). The occupational health physicians have to check the conformity of the vaccinations with the law, and to convince employees and employers to invest in the vaccinal protection for what is not compulsory but medically recommended.