The prevalence of HIV infection among blood donors was analysed, for the five year period from April 1988 to March 1993. All donors were patients' relatives or volunteers; no paid/commercial donors were accepted. Each year between 14,084 and 15,544 donor blood samples were screened by ELISA and those found reactive were tested by Western blot. Western blot positive samples were considered to be infected with HIV. The prevalence rates were 1.5 per 1000 (1988-89), 1.1 per 1000 (1989-90 and 1990-91) 1.9 per 1000 (1991-92) and 3.1 per 1000 (1992-93). When the mean prevalence rate over the first three years [1.3 per 1000 (1988-89 to 1990-91)] was compared to the prevalence in 1991-92 (1.9/1000), increase was statistically significant (P < 0.05). The prevalence rate in 1992-93 (3/1000) was significantly higher than that of the previous year (P < 0.01). These data suggest that the prevalence of HIV infection in blood donors is increasing and this could be a reflection of the rising prevalence of HIV infection in the general population.