The objective of this study was to evaluate and compare the pharmacokinetics of meropenem in premature neonates, both after the first dose and during steady state at day 5, after a 1-minute intravenous administration to evaluate the possibility of twice-daily administration. Seven premature neonates received 15 mg/kg meropenem twice daily on clinical grounds as a 1-minute infusion. After the first dose and during steady state at day 5, serum levels of meropenem were measured for 12 hours after intravenous administration. Meropenem pharmacokinetics at the first dose were studied in seven children (mean birth weight 925 g, mean postnatal age 21 days). Serum concentration-time curves could be described with a one-compartment model. Mean total body clearance was 0.157 L/kg per hour, volume of distribution was 0.74 L/kg, and half-life was 3.4 hours. At day 5 at steady state, pharmacokinetic properties did not differ significantly. No side effects were noted. A 1-minute intravenous administration is feasible. Pharmacokinetic properties are comparable at day 5 compared with the first dose, and half-life is such that twice-daily administration of 15 mg/kg produces adequate serum concentrations.