Abstract: Breastfeeding is a crucial child survival intervention. However,the potential for transmission of viral infections from mother to child presents the dilemma of how best to interpret the benefits and risks of breastfeeding in different settings. In this review,the transmission dynamics, risk factors, and outcomes of infection ofthree chronic viruses transmitted through breast milk:cytomegalovirus,human T-cell lymphotropic virus type 1,and Human immunodeficiency virus(HIV) were compared. An overview of intervention approaches were provided and scientific,policy,and programming gaps in the understanding of these major global infections were discussed.