We reports a six-year-old child with autistic disorder and methadone intoxication. Developmental disorders may mislead the caretakers and doctors to interpret the clinical manifestation and behavioral changes of these patients. Methadone indigestion can be fatal in children even in a tiny amount and cardiac monitoring should be performed at least for the first 24 hours. The pervasive prescription of methadone for detoxification programs and its extensive availability at homes of the addicted parents should point parents, doctors and media to pay more attention to provide safe-home environment for children.