Although ketorolac is commonly used as an analgesic in the pediatric population, there is no information on the pharmacokinetics of ketorolac available for children less than 6 months of age. The objective of this analysis was to construct a population pharmacokinetic model to describe ketorolac disposition in young children. Three neonates and 9 infants, median (range) age 0.4-32 weeks, were administered with 0.5 mg/kg of ketorolac. The data were best described by a 2-compartment model, with an allometric expression to describe body weight effects on clearance. Estimated parameters were clearance [2.8 mL x min(-1) x (kg(0.75))(-1)], intercompartmental clearance (11.5 mL/min), volume of distribution of the central compartment (535 mL), and volume of distribution of the peripheral compartment (322 mL). The clearance values in these neonates and younger group of infants are greater than that reported for older children and adults.