Thirty-two children with refractory partial epilepsy received open-label gabapentin as an additional medication to their antiepileptic drug regimen. Gabapentin was given in a dose ranging from 10 to 50 mg/kg per day (mean dose, 26.7 mg/kg daily). All patients had partial seizures with or without secondary generalization. Compared with baseline, 11 patients (34.4%) had a greater than 50% decrease in seizure frequency, and 4 (12.5%) had a 25% to 50% decrease in seizure frequency. Of the seven children who received the medication for 6 months or longer, two were seizure free and four were almost seizure free (having one seizure every few months). Mean gabapentin concentration was 4.8 micrograms/ml, and mean apparent clearance was 372 ml/kg per hour. The major reported side effects were behavioral. These consisted of hyperactivity, irritability, and agitation that occurred in patients with baseline mental retardation with attention deficit. We conclude that gabapentin can be a useful adjunctive medication in the treatment of refractory partial epilepsy in children.