Breast milk is the ideal food for infants and should be consumed as the exclusive food for the first six months and then be complemented up to two years of age. The aim of this study is to determine breast milk’s content of macro and micronutrient in lactating mothers from the Ribeir?o Preto (SP) region, in Brazil. A cross-sectional study was conducted with breast milk samples of 70 mothers from the city of Ribeir?o Preto (SP). The samples were analyzed in order to determine iron, copper, zinc, calcium and magnesium concentrations. They were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The study was approved by the Research Ethics Committee of the University Hospital, Faculty of Medicine of Ribeir?o Preto, University of S?o Paulo, and all subjects gave written informed consent to participate. The current study revealed that all 70 lactating mothers were healthy and delivered babies more than 38 weeks gestation; 71.4% of them were younger than 30 years and 47.1% were primiparae. The iron, copper, zinc, calcium and magnesium concentrations detected in milk were 2.7 ± 0.4, 0.4 ± 0.02, 3.6 ± 0.2, 142 ± 21.6 and 39.8 ± 4.2 mg/L, respectively. Therefore, it can be concluded that in the present sample, except for calcium, all other mineral concentrations were adequate for the infant’s requirements according to the Dietary Reference Intake (DRI).