Immunization is an important measure to protect HIV-infected children and adults against certain vaccine preventable diseases. However, the antibody response, which is associated with the level of CD4+ T cell count, is frequently impaired in this group of patients. Certain vaccines enhance virus replication and transiently increase HIV viral load. Theoretically, vaccination should be given before the immune status of the patients is suppressed. Inactivated vaccines are generally safe and are beneficial for HIV-infected patients. These vaccines should be administered at appropriate age recommended for immunocompetent individuals. Live vaccines should be used with caution since some of the vaccines may be harmful to patients with severe immunologic suppression. Recommendations for immunization in HIV-infected patients may differ from country to country, depending on the availability and affordability of each vaccine, and the prevalence of each preventable disease. Vaccine trial in HIV-infected patients is needed in order to establish the most appropriate vaccine recommendation for this group of patients.