We evaluated the efficacy and safety of gabapentin administered as monotherapy in an 8-day, randomized, double-blind, dose-controlled, parallel-group, multicenter study comparing dosages of 300 and 3,600 mg/d gabapentin in 82 hospitalized patients whose antiepileptic medications had been discontinued for seizure monitoring. Seizures under study were complex partial seizures with or without secondary generalization. Patients exited the study if they experienced a protocol-defined exit event indicating lack of efficacy. Time to exit was significantly longer (p = 0.0001) and completion rate was significantly higher (53% versus 17%; p = 0.002) for patients receiving 3,600 mg/d gabapentin. Gabapentin was well tolerated by patients in both dosage groups, and no patients exited the study due to adverse events, despite rapid initiation of full dose within 24 hours. These results demonstrate that gabapentin has anticonvulsant activity and is well tolerated when administered as monotherapy in patients with refractory partial seizures.