AIDS has become a problem for not only researchers and medical staff but also for humankind, since its discovery 10 years ago. To prevent and control AIDS, one must understand the pathology of HIV infection, which is the cause of AIDS, in addition to mass education on correct measures for prophylaxis. In this review, we present the present status of HIV infection in Japan, especially in relation to pulmonary disease and tumor, and we introduce the basic research being carried out for the development of HIV vaccine.