Specific genetic conditions may lead to sudden unexpected deaths in infancy, such as inborn errors of fatty acid oxidation and genetic disorders of cardiac ion channels. The disease may present dramatically with severe hypoketotic hypoglycemia, Reye syndrome or sudden death, typically with a peak of frequency around 3-6 month, whilst neonatal sudden death is quite rare. When undetected, approximately 20-25% of infants will die or suffer permanent neurologic impairment as a consequence of the first acute metabolic decompensation. Meanwhile, the advent of newborn screening for metabolic diseases has revealed populations of patients with disorders of fatty acid oxidation (FAO), the most frequent of which is medium chain acyl-CoA dehydrogenase (MCAD) deficiency. Without this screening, affected individuals would likely succumb to sudden infant death syndrome (SIDS). Here we describe an overview of sudden infant death syndrome and inherited metabolic disorder.