Seric IgA, IgE and IgD; antinuclear antibodies and lymphocyte and eosinophil counts were studied in 61 epileptic children; 22 patients were treated with phenobarbital and 39 with hydantoine. The mean length of treatment was 12 months to phenobarbital and 23 to hydantoins. Seric IgA was deficient in 4/36 children taking hydantoins and only 1/20 receiving phenobarbital. IgE mean was increase in hydantoins treated patients and also IgD was found higher than normal in 6 patients. Only one case showed seric antinuclear antibodies but they disappeared with drug withdrawal. The lymphocyte count was normal but an important eosinophilia rise with treatment (phenobarbital or hydantoins). These immunological abnormalities were meanly found in idiopatic epilepsy. These suggest they are produced by anticonvulsivant drugs but also by an important constitutional factor. In this way immunology and epilepsy may be related.