Background: Epilepsy has prevalence about 0.5 - 1% of world population. From many years ago, plants used to treat of various neurological diseases such as seizures. Objective: The anticonvulsant effects of hydroalcoholic extract of Tanacetum sonbolii was examined in male mice. Methods: 60 mice were randomly divided into six groups (n=10), included: A control group (normal saline) and 5 groups receiving Sonbolii extract (150, 300, 600, 900, 1200 mg/kg). 30 min after peritoneal injection of different doses extract or saline, PTZ (85 mg/kg) were injected and the animal immediately transferred to a special cage, and the seizure behavior was evaluated within 30 minutes. Results: The tonic and colonic seizures were significantly reduced in the groups that received extract compared to control group. The onsets of seizures were difference between treated and control animals statistically. Extract were reduced the rate of death during seizures and was prevented the outbreak of tonic - colonic seizures in some case. Conclusion: Our results showed that the extracts of Tanacetum sonbolii have strong anticonvulsant effect, and more complementary studies will be done for identifying the mechanism of action and effective material of Sonbolii exact.