We have reported long-term clinical follow-up for two siblings with Lafora disease, a brother and sister, one of whom autopsied. Both siblings had repeated attacks of severe myoclonus, tonic and tonic-clonic convulsions, and intractable status epilepticus. The addition of orally administered zonisamide brought about striking effective seizure control for about 12-14 years in both patients, relieving not only myoclonus and generalized tonic-clonic seizures but also intractable status epilepticus.