BACKGROUND Infant formulas are typically manufactured using skimmed milk, whey proteins, and vegetable oils, which excludes milk fat globule membranes (MFGM). MFGM contains polar lipids, including sphingomyelin (SM). OBJECTIVE The objective of this study was comparison of infant plasma SM and acylcarnitine species between infants who are breastfed or receiving infant formulas with different fat sources. METHODS In this explorative study, we focused on SM and acylcarnitine species concentrations measured in plasma samples from the TIGGA study (ACTRN12608000047392), where infants were randomly assigned to receive either a cow milk-based infant formula (CIF) with vegetable oils only or a goat milk-based infant formula (GIF) with a goat milk fat (including MFGM) and vegetable oil mixture to the age ≥4 mo. Breastfed infants were followed as a reference group. Using tandem mass spectrometry, SM species in the study formulas and SM and acylcarnitine species in plasma samples collected at the age of 4 mo were analyzed. RESULTS Total SM concentrations (∼42 μmol/L) and patterns of SM species were similar in both formulas. The total plasma SM concentrations were not different between the formula groups but were 15 % (CIF) and 21% (GIF) lower in the formula groups than in the breastfed group. Between the formula groups, differences in SM species were statistically significant but small. Total carnitine and major (acyl) carnitine species were not different between the groups. CONCLUSIONS The higher total SM concentration in breastfed than in formula-fed infants might be related to a higher SM content in human milk, differences in cholesterol metabolism, dietary fatty acid intake, or other factors not yet identified. SM and acylcarnitine species composition in plasma is not closely related to the formula fatty acid composition. This trial was registered at Australian New Zealand Clinical Trials Registry as ACTRN12608000047392.