Muscarinic M1 and M2 receptors are widely distributed in the brain and contribute tovarious physiological and pathological functions. It is well known that enhancement ofcholinergic activity produces convulsions in animals. Pilocarpine, the M1 muscarinicreceptor agonist, is commonly used to induce seizures in rodents. On the other handit has been reported that fasted rats and mice pretreated with the M1 and M2 receptorantagonist atropine, scopolamine or biperiden develop convulsions after food intakeindicating cholinergic hypoactivity as the underlying mechanism. This review willpresent pharmacological data for the M1 and M2 receptors in the brain and focus onthe contrasting findings related to their contribution to convulsions.