Abstract: In this investigation, the effects of percolated and suxhelet Methanolic extract of aerial parts of Rosmarinus officinalis L. on generalized seizure induced by picrotoxin was studied. The study was performed on groups of 10 animals pretreated with different doses of percolated (50, 200, 500 and 1000 mg kg-1) and suxhelet (50 and 100 mg kg-1) extracts of this plant by intraperitoneally (i.p.) injection. After 20 min each animal received picrotoxin 12 mg kg-1 for induction of seizure. Latency of onset time of seizure, duration of seizure, death time and mortality rate were determined. The results showed that latency of seizure was increased in groups that pretreated with different doses of extract (p<0.01). The doses of 200 and 500 mg kg-1 of extract increased the duration of seizure compared with control group (p<0.01). The severity of seizure was milder in treated group with extract. The death time also increased with doses of 50, 200 and 500 mg kg-1. The percolated extract of R. officinalis was more effective but not significant than suxhelet extract. The extracts have no effect on mortality rate. It seems that the R. officinalis extract has anticonvulsant activity on generalized seizure induced by picrotoxin in mice. Overall the more effective dose of extract was 50 mg kg-1 and more experiments are needed in this field.