Controversy still exists concerning the pathogenesis of necrobiosis lipoidica (diabeticorum?)1and the relationship of this disease to granuloma annulare. The purpose in undertaking this study was to glean some information which might further knowledge regarding these problems. The material consisted of histologic sections obtained in 41 cases of necrobiosis lipoidica diabeticorum and 33 cases of granuloma annulare collected since 1934 at the University of Minnesota. The clinical features of both diseases are so well known that they will not be discussed in this paper. Certainly the differences are so striking in most cases that differentiation offers little difficulty. Among the articles which cover various aspects of necrobiosis lipoidica diabeticorum in more or less detail are those by Oppenheim1a; Urbach2; Balbi3; Zeisler and Caro4; Michelson and Laymon5and, more recently, Gottron6; Boldt7; Hildebrand, Montgomery and Rynearson,8and Ellis and Kirby-Smith9Detailed