A positive effect of breastfeeding on the mother-infant relationship is often assumed in the scientific literature, but this has not been systematically reviewed. This review aims to clarify the role of breastfeeding in the mother-infant relationship, which is conceptualized as the maternal bond toward the infant and infant attachment toward the mother. Our findings indicate that theoretical mechanisms through which breastfeeding may enhance the maternal bond or infant attachment (i.e., endocrine and sensory factors involved in breastfeeding) can be found in both humans and animal models. However, the few empirical studies investigating this association have not found convincing support for a relation between breastfeeding and the quality of the mother-infant relationship. We therefore conclude that assumptions on a positive role of breastfeeding on the mother-infant relationship are not supported by empirical evidence, and recommendation of breastfeeding should solely be based on its well-documented positive effects on infant and maternal health. (Contains 1 table.)