Mechanically ventilated children usually require a combination of sedation (morphine = M, diazepam = D) and paralysis (pancuronium = P) to minimize anxiety, discomfort, and the risks of self-extubation, tracheal injury, and pulmonary barotrauma. We sought to determine whether our use of MDP varied with patient age. Cases where the dosage of MDP would be influenced by neurological, hemodynamic, or painful diagnoses were excluded. The 36 cases selected were divided according to age into three groups (< 4 months = A, 4-18 months = B, > 18 months = C). The daily sum of MDP dosages was calculated for each of the 326 study days, a mean of 9 study days for each case. The median daily drug usage in group B (2.3 mg/kg/day) was twice that in either group A (younger) or group C (older) (both p < 0.001). This finding may be explained by developmental changes in physiology, pharmacology, and behavior, and may have been influenced by a paradoxical drug effect or multiple drug antagonism.