Two cases of idiopathic epilepsy are reported. In the first, epileptic convulsions disappeared completely during an acute infection and the patient's mental condition showed a remarkable improvement. In the second, after an acute febrile illness in 1931, the patient has since had only two fits. His mental condition shows a very striking improvement. Protein skin tests were performed on twenty -five male patients suffering from idiopathic epilepsy and on twenty -five non -epileptic controls. Among the former, 36% were positive, among the latter, 4%. Sensitiveness, as indicated by positive skin reactions was found to be increased before, and diminished, for a variable period after a fit or series of fits. A few hours after an injection of Pyrifer, it had disappeared. completely. Non -specific desensitisation by means of Pyrifer was attempted in the case of those showing multi- sensitivity. All showed definite mental improvement. In two cases the fits were reduced by 50% and 38% respectively, while in the third case, there was no reduction in the number of fits. Of those treated with Peptone, two improved mentally, while the third showed no noticeable improvement. The effect on the incidence of fits was not so striking as in the case of Pyrifer. The essential features of Allergy are outlined. Evidence is adduced in support of the view that Allergy is a factor in the causation of certain cases of essential Epilepsy. Other methods of treatment are briefly described. The writer urges the investigation of all cases of idiopathic epilepsy from the allergic point of view and the carrying out of protein skin tests. He strongly advocates some form of desensitisation treatment in those cases which appear to have an allergic basis.