Late presentation is common among African HIV-1–infected infants. Incidence and correlates of mortality were examined in 99 infants with HIV-1 diagnosis by 5 months of age. Twelve-month survival was 66.8% (95% confidence interval: 55.9–75.6%). World Health Organization stage 3 or 4, underweight, wasting, microcephaly, low hemoglobin, pneumonia and gastroenteritis predicted mortality. Early HIV-1 diagnosis with antiretroviral therapy before symptomatic disease is critical for infant survival.