BACKGROUND: Starting lifelong antiretroviral therapy (ART) in HIV-infected pregnant women may decrease HIV progression and transmission, but adherence after delivery may be difficult, especially for asymptomatic women. We evaluated disease progression among HIV-infected women not on ART with CD4 lymphocyte counts above 200 cells per microliter at delivery. METHODS: We analyzed risk of death, progression to AIDS (stage IV or CD4 < 200 cells per microliter), or to CD4 count <350 1 year after delivery among postpartum women enrolled to a prevention of breastfeeding transmission trial using the Kaplan-Meier method. In the primary analysis, women were censored if ART was initiated. RESULTS: Among 1285 women who were not WHO stage IV or less at 6 weeks postpartum, 49 (4.3%) progressed to stage IV/CD4 <200 cells per microliter or death by 1 year. Progression to CD4 <200 cells per microliter or death occurred among 16 (4.3%) of 441 women with CD4 count of 350-549 cells per microliter and 10 (1.6%) of 713 with CD4 counts >550 cells per microliter at delivery. CD4 <350 cells per microliter by 12 months postpartum occurred among 116 (37.0%) of 350 women with CD4 count 400-549 cells per microliter and 48 (7.4%) of 713 with CD4 count >550 cells per microliter at delivery. CONCLUSIONS: Progression to AIDS or CD4 count <350 cells per microliter is uncommon through 1 year postpartum for women with CD4 counts over 550 cells per microliter at delivery, but occurred in over one third of those with CD4 counts under 550 cells per microliter. ART should be continued after delivery or breastfeeding among women with CD4 counts <550 cells per microliter if follow-up and antiretroviral adherence can be maintained.