Many theories have been advanced as to the cause of dermatitis herpetiformis and the relation between pemphigus vulgaris and dermatitis herpetiformis, since many so-called transition cases have been described. Dostrovsky, Gurevitch and Ungar1 have recently summarized the various theories advanced by Urbach and his co-workers,2 Welsh and O'Leary,3 Bernhardt4 and others and have divided their reports into four main classes, dealing with infectious, toxic, virus (neurotropic) and endocrine causation. There is considerable evidence to support each of these theories, but none completely explains the various characteristics of the disease. Urbach and his associates,2 by inoculating rabbits with material obtained from patients with dermatitis herpetiformis and with pemphigus vulgaris, have produced experimentally a similar clinical and histologic picture. Immunologic investigations indicated a cross immunity between the virus of pemphigus and that of dermatitis herpetiformis, and it is these authors' conclusion that symptoms of pemphigus vulgaris and