Fetal alcohol spectrum disorder is a range of birth defects associated with prenatal alcohol exposure. Fetal alcohol syndrome (FAS) is the most serious form of fetal alcohol spectrum disorder. Infants with FAS are prone to death because of various physical abnormalities. Consequently, infants with FAS may be presented in the medicolegal investigation as a form of sudden unexpected death in infancy. The author reported a 6-month-old male infant who was found dead at home. The history of maternal ethanol consumption during pregnancy was obtained. The infant was diagnosed with FAS at the autopsy because he was presented with postnatal growth retardation, multiple facial abnormalities, and abnormal brain structures, which met the criteria of FAS. The cause of death was severe aspiration pneumonia. The purposes of this case report are to show an uncommon manifestation of sudden unexpected death in infancy case for the forensic pathologists and to emphasize on the national healthcare problem.