60 preterm neonates ranging in gestational age from 22 to 32 weeks will be recruited from the NICU. Stratification by gestational age will be done to ensure broad representation. The decision to initiate morphine therapy will be based solely on clinical indications. Prior to morphine dosing, a biochemical assessment of hepatic and renal function will be obtained. A 0.05 mg/kg loading dose of morphine will be given by an intravenous infusion over 30-minutes in preterm neonates with a gestational age of less than 29 weeks, followed by a continuous infusion of 0.005 mg/kg/h, whereas a loading dose of 0.1 mg/kg will be given in preterm neonates with a gestational age of 29 weeks or more followed by a continuous infusion of 0.01 mg/kg/h. Pain assessment will be performed at baseline (prior to study medication administration) and at .5, 1, 2, 4, 8, 12 and 24 hours after the dose. At each of these time points infants will be videotaped for two minutes with two cameras. Videotapes will be scored afterward using standard validated pain assessment tools for preterm infants.