BACKGROUND Early-life nutrition may influence later body composition. The effect of breastfeeding and formula feeding on infant body composition is uncertain. OBJECTIVE We conducted a systematic review and meta-analysis of studies that examined body composition in healthy, term infants in relation to breastfeeding or formula feeding. METHODS PubMed was searched for human studies that reported the outcomes fat-free mass, fat mass, or the percentage of fat mass in breastfed and formula-fed infants. Bibliographies were hand searched, and authors were contacted for additional data. The quality of studies was assessed. Differences in outcomes between feeding groups were compared at prespecified ages by using fixed-effects analyses except when heterogeneity indicated the use of random-effects analyses. RESULTS We identified 15 studies for inclusion in the systematic review and 11 studies for inclusion in the meta-analysis. In formula-fed infants, fat-free mass was higher at 3-4 mo [mean difference (95% CI): 0.13 kg (0.03, 0.23 kg)], 8-9 mo [0.29 kg (0.09, 0.49 kg)], and 12 mo [0.30 kg (0.13, 0.48 kg)], and fat mass was lower at 3-4 mo [-0.09 kg (-0.18, -0.01 kg)] and 6 mo [-0.18 kg (-0.34, -0.01 kg)] than in breastfed infants. Conversely, at 12 mo, fat mass was higher in formula-fed infants [0.29 kg (-0.03, 0.61 kg)] than in breastfed infants. CONCLUSIONS Compared with breastfeeding, formula feeding is associated with altered body composition in infancy.