THIS STUDY deals with the effectiveness of ethosuximide (Zarontin) in the treatment of 100 patients with recurrent, short, mild seizures, mostly typical petit mal attacks. Interest in the succcinimides began with the demonstration of their anticonvulsant effects in experimental animals by Miller et al. and by Chen et al. This led to the clinical evaluation of phensuximide (Milontin) and, later, of methsuximide (Celontin). Although both of these compounds have a place in the treatment of convulsive disorders, they are of limited value in petit mal. The third succinimide, ethosuximide, which is the subject of this report, was found to be highly protective against pentylenetetrazol (Metrazol)-induced seizures in experimental animals. A number of encouraging reports on its effectiveness in controlling petit mal epilepsy have appeared. Method The 100 patients reported on are from the Seizure Clinic population at the Columbia-Presbyterian Medical Center, or are private patients under the management of neurologists