Nafimidone is a candidate anticonvulsant agent. The anticonvulsant effectiveness of nafimidone was evaluated in the kindled amygdaloid seizure model in rats. Nafimidone (25-50 mg/kg) significantly reduced supranthreshold elicited afterdischarge length and seizure severity only at doses with some prestimulation toxicity. The maximum anticonvulsant effectiveness for the 25 mg/kg i.p. dose of nafimidone was seen between 15 and 30 min utilizing a suprathreshold kindling paradigm. Nafimidone did not significantly elevate seizure thresholds at the doses tested; however, nafimidone (3.1-50 mg/kg) reduced the severity and afterdischarge duration of threshold elicited seizures in a non-dose response manner. Nafimidone is a new antiepileptic drug which may be effective in partial onset seizures in humans.