We report 2 cases of type I glycogen storage disease (Von Gierke's disease) discovered in 2 brothers at the age of 7 and 5 years, respectively. Both developed hepatic adenoma at the age of 19 and 17. Hepatocellular carcinoma occurred in the older brother the discovery of adenoma 4 years after. The frequency of these tumors in patients with type I glycogen storage disease raises problems concerning the treatment and modality of regular surveillance of the liver in these patients. The policy for the detection and treatment of these tumors, and particularly the indications for liver transplantation are discussed.