Organic acidurias are a group of diseases that may start their clinical presentation from the first days of life. These diseases are diagnosed by urinary organic acids profile analysis by gas chromatography coupled to mass spectrometry (GC-MS) where presence or increments of metabolites characteristic of specific organic acidurias may be detected. In human metabolism several organic acids are synthesized from diet through metabolic pathways involved i degradation of amino acids, fatty acids and carbohydrates. Previous studies have shown that dietary habits ma influence the organic acid excretion profile, however, most studies have evaluated infants, children and adults rate than newborns. For this reason, the aim of the study was to describe the organic acids excretion profile of newborn. The achieve such aim a semi quantitative analysis of the organic acids excretion profile was performed by GC-MS in urin samples from newborns feed with breast milk and infant formulas. In the profiles obtained it was observed the excretion of 35 short and medium chain organic acids including metabolites derived from Krebs cycle, and the metabolism < amino acids and fatty acids. In addition changes in the organic acids excretion profile depending on the diet were observed. Such changes may affect the interpretation of the profile since it was detected the presence of metabolite associated to organic acidurias as well as changes in the levels of several organic acids between both populations.