Of 28 infants diagnosed with HIV infections after the recommended time of breastfeeding cessation in a large clinical trial (the Breastfeeding, Antiretrovirals and Nutrition Study), 19 (68%) were first detected more than 6 weeks (and up to 168 days) after recommended weaning. The current WHO recommendation for HIV testing of infants is at 6 weeks or more after weaning; these data argue for repeat HIV testing of infants up to 6 months after breastfeeding cessation, so that no infant HIV infections are missed.