Morsuximide is succinimide derivative patented by Chinoin Gyogyszer es Vegyeszeti Termekek Gyara Rt. as an antiepileptic agent. In cats, Morsuximide had mild hypnotic effects when given i.p., and the status epileptic induced by Tetracor was brought under control. Tetracor, given after the administration of Morsuximide, caused only subconvulsive seizures in cats accompanied by an occasional jerk of the skeletal musculature. When 16 epileptic patients were treated with oral Morsuximide (1.0-2.0 g. daily for an av. of 42 days) the drug produced a favorable effect in all forms of human epilepsy, particularly in cases of psychomotor attacks, atypical forms, and petit mal. The major type of epilepsy (grand mal) did not respond to the drug therapy as markedly as the other forms, although drug caused some improvement in these cases.