A 24-year-old man with respiratory failure, severe bradycardia, and coma following heroin overdose was successfully resuscitated using endotracheally administered naloxone hydrochloride (Narcan). Post-treatment naloxone assays demonstrated the presence of large amounts of naloxone in the patient's blood and urine. Serial serum naloxone levels over the ensuing three hours showed pharmacokinetics which appear similar to those previously reported for intravenous naloxone.