Repeated injections of naloxone by hydrochloride, a pure narcotic antagonist, were administered to a 3,320-gm 4-week-old boy for treatment of an accidental morphine overdose. The infant received frequent naloxone hydrochloride injections (0.2 mg per injection) during the first 12 hours of therapy to reverse morphine-induced apnea, hypothermia, and flaccidity. A cumulative dose of 2.73 mg of naloxone hydrochloride (0.822 mg/kg) was administered over 27 hours without apparent adverse effect or evidence of toxicity.