Clinical, laboratory, and postmortem studies on two cases of generalized glycogenosis diagnosed, and studies during life, and the family history of a third case are presented. An instance of consanguinity and of an afflicted brother and sister are noted in this small series. Serial electrocardiograms of both infants showed progressive left ventricular hypertrophy and variability in P, Q, S-T, and T waves over a period of months. Tracings of one patient revealed shifting atrial foci, ventricular coupling, and slight aberration in some of the ventricular complexes. Unexplained mild fructosuria was noted in one patient. Staining of circulating leukocytes for glycogen appears to be an unreliable diagnostic test.