We studied the role of oligoantigenic diets in 63 children with epilepsy; 45 children had epilepsy with migraine, hyperkinetic behavior, or both, and 18 had epilepsy alone. Of the 45 children who had epilepsy with recurrent headaches, abdominal symptoms, or hyperkinetic behavior, 25 ceased to have seizures and 11 had fewer seizures during diet therapy. Headaches, abdominal pains, and hyperkinetic behavior ceased in all those whose seizures ceased, and in some of those whose seizures did not cease. Foods provoking symptoms were identified by systematic reintroduction of foods, one by one; symptoms recurred with 42 foods, and seizures recurred with 31; most children reacted to several foods. Of 24 children with generalized epilepsy, 18 recovered or improved (including 4 of 7 with myoclonic seizures and all with petit mal), as did 18 of 21 children with partial epilepsy. In double-blind, placebo-controlled provocation studies, symptoms recurred in 15 of 16 children, including seizures in eight; none recurred when placebo was given. Eighteen other children, who had epilepsy alone, were similarly treated with an oligoantigenic diet; none improved.