The efficacy of second-line antiepileptic drugs (AEDs) was evaluated in the treatment of 66 patients with complex partial seizures who had previously failed first-line AEDs. Methsuximide, valproate, or clorazepate had eliminated seizures in 11% of the patients at the end of the study. However, these good results deteriorated on longer follow-up and were not expected to be permanent. It is recommended that suitable patients with partial epilepsy be referred for surgical evaluation after failing the first-line AEDs, and that second-line AEDs be reserved for nonsurgical candidates.