In this study, the correlations of human immunodeficiency virus type 1 (HIV-1) RNA levels in blood plasma, vaginal secretions, and cervical mucus of 52 HIV-1-infected women were determined. The amount of cell-free HIV-1 RNA in blood plasma was correlated with that in vaginal secretions (Spearman's rank correlation coefficient (r) = 0.64 P < .001 In both blood plasma and vaginal secretions, the amounts of cell-free and cell-associated HIV-1 RNA were highly correlated (r = 0.76, P < .01 and r = 0.85, P < .01, respectively). Cell-free HIV-1 RNA levels in blood plasma and vaginal secretions were negatively correlated with CD4+ T lymphocyte count (r = −0.44, P < .01 and r = −0.40, P < .01, respectively). Similar to the effect observed in blood plasma, initiation of antiretroviral therapy significantly reduced the amount of HIV-1 RNA in vaginal secretions. These findings suggest that factors that lower blood plasma virus load may also reduce the risk of perinatal and female-to-male heterosexual transmission by lowering vaginal virus load.