The increasing number of immunocompromised persons both in industrialized countries and the developing world are at higher risk of acquiring certain diseases. Health professionals and doctors need to implement adequate vaccination strategies. According to the type of the underlying disease, its course and the therapy, the response to vaccine may be suboptimal. Thus it is important to immunize when possible before treatment is initiated and to respect an adequate timing for the immunization after treatment or transplantation. Clear recommendations need to be provided to physicians. Household members and medical staff need to be adequately immunized in order to avoid additional risks of transmission to the immunocompromised patient. Finally, there is a need for more potent vaccines using new adjuvants or immunoregulators, new vaccines such as for meningitis B and combined vaccines with good immunogenicity in order to simplify immunization schedules and still provide longlasting protection.