BACKGROUND: Prevention-of-mother-to-child-transmission (PMTCT) programs have made it possible to achieve dramatic reductions in the rate of vertical HIV transmission. However, high attrition, particularly after delivery, has limited the impact of these interventions for HIV-exposed infants who remain at risk through the end of breastfeeding. DESIGN AND METHODS: A review of current literature on early infant diagnosis (EID) testing and country experience in low-and middle-income countries. RESULTS: While PMTCT programs report reduced rates of infection among infants tested at 2 months of age, too few services are focused on retention of HIV-exposed infants in care. An unacceptably large proportion of HIV-exposed and HIV-infected infants remain unidentified. While the complexities of EID have been simplified with the development of optimized commodities and tools to improve service delivery, the inaccessibility and inadequate uptake of EID services has resulted in lag of care for the millions of HIV-exposed infants who remain unidentified. Coverage of EID testing remains low and there are many HIV- infected infants or at risk of infection who may not enter the health system through PMTCT programs. Waiting for HIV-infected children to present sick is not an adequate strategy for identifying and linking infants to treatment. Several interventions suggest a potential to expand access to EID testing, while more aggressive testing strategies may ensure children can be captured at any point of contact with the health system. CONCLUSIONS: Programs focused on preventing vertical transmission need to increase their commitment to child-centric interventions and broaden their measure of success to reflect infants who test negative at the end of the exposure period. This paper argues that EID is a key strategy to retaining HIV-exposed infants through the end of the exposure period, as it provides an opportunity to offer early clinical care and continuous follow up. It is imperative that maternal and child survival programs become sensitized to the urgency of early identification of HIV in infants and their retention in care.