This analysis of gentamicin pharmacokinetics involved 15 neonates supported by extracorporeal membrane oxygenation (ECMO). Two sets of blood samples were obtained from each neonate while supported by ECMO. The mean volume of distribution, elimination half-life, and clearance calculated from the first set of samples were 0.62 liters/kg, 7.6 hours, and 1.17 ml/kg/minute, respectively. Mean values from the second set of samples were 0.61 liters/kg, 7.9 hours and 0.99 ml/kg/minute, respectively. There were no statistical differences (p greater than 0.05) between the pharmacokinetics calculated from the first and second set of samples. A comparison of our results with those of others involving neonates not supported by ECMO failed to demonstrate any major impact of ECMO on the pharmacokinetics of gentamicin.