CD4+-lymphocyte counts (LCs) play a crucial role in the management and monitoring of HIV infection. Variability in CD4+ LCs has been reported to occur as a result of measurement techniques and/or biological variations. We report on the CD4+ LCs of healthy human immunodeficiency virus (HIV)-seronegative adults in Botswana. Samples were obtained from HIV-seronegative blood donors. The median CD4+ LC was 726 cells/mm3 (for females, 782 cells/mm3; for males, 698 cells/mm3). The median CD8+ LC was 488 cells/mm3 (for females, 494 cells/mm3; for males, 485 cells/mm3). The median CD4+-to-CD8+ ratio was 1.57 (for females, 1.66; for males, 1.51). Our findings of low CD4+ LCs among HIV-negative adults in Botswana are significant and have important implications for the management of HIV disease in the population of this sub-Saharan African country.