During the past few years we have been impressed with the fact that in children with severe diabetes mellitus which has not been brought under satisfactory control, well marked enlargement of the liver may occur. In this paper we are reporting studies of 60 children (54 living and 6 dead) with pronounced hepatomegaly from among 1,077 patients (815 living and 262 dead) in whom the onset of diabetes occurred at the age of 15 years or under; the list as here presented is not complete. In view of the large number of cases we regard enlargement of the liver as one of the outstanding complications of uncontrolled severe juvenile diabetes. The cause of the increase in size, the nature of the enlargement—whether fatty, glycogenous or otherwise—and the specific treatment present difficult and interesting problems. As Hanssen1has pointed out, little mention of gross hepatomegaly in human diabetes is to