The review draws from surveillance data bases maintained by the Centers for Disease Control, the National Institute on Drug Abuse, the National Institutes of Health, and the Department of Defense. An examination of the prevalence of HIV infection among groups at recognized risk focuses on homosexual and bisexual men, intravenous drug users, hemophiliacs, and heterosexual partners of persons with HIV infection or at recognized risk. The prevalence of HIV infection among selected segments of the general population includes blood donors, civilian applicants for military service, job corps entrants, sentinel hospital patients, and newborn infants and women of reproductive age. Consideration of HIV infection prevalence in special settings covers prisoners, prostitutes, tuberculosis patients, and college students. HIV infection prevalence is also examined in terms of geography, age, sex, race, and ethnicity. Other issues reviewed are HIV infection prevalence among heterosexuals without acknowledged high-risk exposure, HIV infection trends over time and the incidence of new infection, and implications for the national estimate of HIV infection prevalence. 24 references, 15 tables, and 13 figures.