Background and Objective: Epilepsy is the most common neurological disorder after stroke. The aim of the present study was to evaluate the effect of hydroalcoholic extract of Heracleum persicum on pentylenetetrazol (PTZ) - induced seizure in mice. Materials and Methods: In this study, 30 male mice were divided into five groups. 30 minutes after IP administration with different doses of extract (75,150, 300, 600mg/kg), PTZ (80 mg/kg) was injected to animals and they were instantly transferred to a special cage. Consequently, the convulsive behaviors of the mice were recorded by a camera as long as 20 minutes and the data were converted into seconds to be considered for analysis. Results: The results indicated that hydroalcoholic extract of Heracleum persicum has a significant effect on threshold tonic seizure in doses of 150 mg/kg, 300mg/kg and 600 mg/kg. In clonic phase, threshold increased slightly with an increase in doses of extract. In tonic-clonic phase, threshold increase was significant only in doses of 150 mg/kg and 900 mg/kg. This extract significantly decreased seizure duration time both in tonic and tonic-clonic phases upon dose increasing. Conclusion: The results of the present study imply that injection of hydro-alcoholic extracts of Heracleum persicum led to anticonvulsant activity. This extract augmented the onset of different seizure phases while reduced duration of tonic and tonic-clonic phases.