The convulsant effects of four doses of picrotoxin (PX) - 2, 3, 4, and 6 mg/kg s.c. - were evaluated in the first part of the study. The 4- mg/kg dose, which elicited minimal seizures in all animals, generalized tonic-clonic (major) seizures in 75 % of rats and fatal outcome in 69 % of rats, was chosen for the second part, i.e. for testing the anticonvulsant action of clonazepam (Rivotril1* Roche, 0.1 or 1 mg/kg i.p.). Clonazepam exhibited a dose-dependent action against PX-induccd seizures, being more efficient against major than against minimal seizures.