A 31-month-old girl required constant intravenous (IV) infusion of naloxone hydrochloride to treat codeine-induced respiratory and CNS depression. The infusion rate was 0.4 mg/hr (27 micrograms/kg/hr) over nine hours, without apparent side effects or evidence of toxic effects, for a total naloxone hydrochloride dose of 4.1 mg (280 micrograms/kg). Constant naloxone hydrochloride infusion at an initial rate of 0.4 mg/hr in pediatric narcotic poisoning should be considered if the patient responds inadequately to an initial 0.01-mg/kg bolus, requires repeated administration to reverse narcotic-induced effects, or has ingested long-acting agents. Continuous IV naloxone infusion is a convenient, safe, and effective method to treat narcotic overdose.