Metabolic diseases can vary as much in clinical presentation as they can in classification, and neonates and infants frequently present with symptoms similar to those seen with other emergencies. Vomiting, alterations in neurologic status, and feeding difficulties are the most prominent features of metabolic emergencies. This article discusses the recognition and management of specific disorders, including diabetic ketoacidosis, congenital adrenal hyperplasia, inborn errors of metabolism, and thyrotoxicosis. Also highlighted are specific laboratory entities, including hypoglycemia, hyponatremia, and metabolic acidosis.