This article describes the National AIDS Prevention and Control Program in Cuba and presents the results of serologic studies of HIV prevalence. As of 30 May 1988 2,224,748 individuals (approximately one-third of the Cuban population plus 32,750 foreigners) of sexually active age from high-risk and other population groups had been screened to detect HIV antibody. Among resident Cubans a total of 227 HIV infections were found, indicating a prevalence of 0.01 seropositives per 100 people tested. The seroprevalence of HIV among blood donors is on the order of one infection per 50,000 people, and appears to have declined since 1986. The seroprevalence of HIV among groups at risk is relatively low compared to that found among similar groups in other countries.