To test the hypothesis that fluoxetine may be a useful adjunct to antiepileptic therapy, we treated with fluoxetine (20-40 mg/day) nine patients suffering from medically intractable epilepsy with daily seizures. Five patients remained unchanged and four worsened. Worsening was more evident at 40 mg/day. One patient improved when receiving the lower dose (20 mg/day) and worsened with the higher dose (40 mg/day). These data suggest: (1) that fluoxetine is not effective as add-on antiepileptic treatment; (2) that caution should be exerted when using fluoxetine as an antidepressive treatment in epileptic patients.