The etiology and pathogenesis of idiopathic nephrotic syndrome remain obscure. Several investigations have reported a role for allergy in the development and maintenance of this disease, especially in childhood. We have studied 20 pediatric patients with relapses of nephrotic syndrome related in time to respiratory symptoms. Sensitization was demonstrated to one or more allergens in 7 patients with episodes of proteinuria of seasonal tendency. Preventive management with disodium cromoglycate was successful in preventing new relapses in 3 patients; specific immunotherapy was assayed in another 2 without beneficial outcome. There appears to be a pathogenic relationship between respiratory allergy and proteinuria in some cases of nephrotic syndrome.