To assess the degree of HIV endemicity and the extent of its penetration into the general population in Bophuthatswana, a sentinel network of all the 11 hospitals and 3 prisons in the country was established in 1987. In addition, a population seroprevalence study was conducted in 1989. Between 5 January 1987 and 31 December 1989, serum specimens from 19,941 persons of all ages were tested for HIV. Overall, 34 subjects were found to be seropositive (prevalence 0.17%). Between 1 April and 31 August 1989, an HIV seroprevalence survey in a stratified multistage random sample of the resident population aged 15 years or older was also conducted. In this study, 2,111 persons were sampled but HIV antibody tests were done on 1553 only. A total of 12 serum specimens (0.8%) were reactive for anti-HIV by both Abbott EIA and Serodia HIV kits. However, in only 2 of these 12 sera was Western blot analysis positive. The overall prevalence of HIV infection in this study was 2/1553 participants (0.13%). These results demonstrate not only that HIV infection and the potential for its transmission are present in the Republic of Bophuthatswana but that they call for energetic and well-targeted control programmes.