Objective: Inborn errors of metabolisms (IEMs) are a heterogeneous group of disorders that can occur as a result of inherited or spontaneous mutations, are rare when considered alone, but have many diseases as a group. Although they are generally thought of as diseases of the neonatal period, 50% of these also occur outside the neonatal period, and some are not diagnosed until adulthood. The aim of this study is to examine the frequency, clinical and laboratory features of inborn errors of metabolism in the neonatal period. Methods: The results of 60 patients who were diagnosed with IEMs as a result of the study, out of 1400 patients who were followed up and treated in the Children's Hospital Neonatal Intensive Care Unit between January 2018 and December 2020, were evaluated. Results: In this study, it consisted of 60 cases, 30 (%50) of which were girls and 30 (%50) were boys (50%). The median age of the patients included in the study was 3 (1-25) days at admission, median weight was 3100 (1000-4000) g, and gestational week was found to be median 39 (27-40) weeks at admission. The most common complaints were feeding difficulty 43(72%), tachypnea 27 (45%) and vomiting 5 (8.3%). The most common laboratory findings were metabolic acidosis 39 (65%) and 36 (60%) hypoglycemia. There was a history of consanguinity in 46 (76.6%) cases, and a history of sibling death in 30 (50%). The mother had a history of abortion in 5 (8.3%) patients who did not have a history of sibling death. The most common diagnoses were Urea cycle disorder 13 (21.7%), organic acidemia 12 (20%), galactosemia 10 (16.7%) and amino acid metabolism disorders 9 (15%). Conclusion: Inborn errors of metabolisms, which are a group of diseases that can occur in different spectrums with clinical, biochemical and genetic heterogeneity, should be kept in mind especially in regions where consanguineous marriages are high. In cases such as metabolic acidosis, which presents with nonspecific symptoms such as malnutrition, tachypnea and jaundice in the neonatal period and cannot be explained in laboratory examinations, care should be taken and they should be referred to centers for further investigation.