Two-dimensional deconvolution techniques are used here to reconstruct age-specific human immunodeficiency virus(HIV) infection rates in the United States from surveillance data on acquired immunodeficiency syndrome (AIDS). This approach suggests that 630,000 to 897,000 adults and adolescents in the United States were living with HIV infection as of January 1993, including 107,000 to 150,000 women. The estimated incidence of HIV infection declined markedly over time among white males, especially those older than 30 years. In contrast, HIV incidence appears to have remained relatively constant among women and minorities. As of January 1993, prevalence was highest among young adults in their late twenties and thirties and among minorities. An estimated 3 percent of black men and 1 percent of black women in their thirties were living with HIV infection as of that date. If infection rates remain at these levels, HIV must be considered as endemic in the United States.