Introduction: Epilepsy is one of the most common and chronic neurological disorders. It appears periodically and usually is concomitant with unpredictable seizures due to abnormal discharge of brain neurons. In this study, we investigated the anticonvulsant effect of ascorbic acid (AA) on seizures induced by pentylenetetrazole (PTZ) in male rats. Methods: In this study PTZ (37 mg/kg) was injected every other day to induce kindling in male rats. AA (12.5, 25 and 50 mg/kg) was administered into the right lateral ventricle 30 minute before every PTZ injection. The seizure parameters were measured during 30 min after PTZ injection. Results: Administration of 12.5 mg/kg of AA increased stage 4 latency compared to vehicle group. Conversely, 50 mg/kg of AA decreased stage 1 and 2 latency, increased stage 5 duration and decreased number of PTZ injections needed to achieve stage 5 seizure compared to vehicle treated animals. Conclusion: It seems that the AA has dual effects on seizure parameters induced by PTZ. Low doses (12.5 mg/kg) have protective effects while high doses (50 mg/kg) have proconvulsant effects on seizure.