Older patients with type I glycogen storage disease (GSD) develop hepatic adenomas that may undergo malignant transformation. Despite their similarity to oral contraceptive-related hepatic tumors, only one previous report has even mentioned hemorrhage in GSD-related hepatic tumors. We recently followed a 20-year-old patient with type Ia GSD and a 10 cm focal defect in the left lobe of the liver; angiography suggested that this was a benign adenoma. At 22 years of age, after an acute symptomatic episode, repeat studies (ultrasonography and angiography) revealed a 2 cm increase in diameter of the hepatic mass. Imminent tumor rupture was of grave concern; thus the patient was admitted to the hospital and given 2 weeks of constant glucose administration by central venous line in the hope of improving her metabolic abnormalities. After resolution of the coagulopathy and metabolic disorders, the patient safely underwent surgical enucleation of the tumor. Pathologic examination of the tumor revealed that the patient had indeed hemorrhaged into a typical hepatic adenoma that had focuses of hepatocellular dysplasia. She has done well without evidence of tumor recurrence for 3 years since the operation. We conclude that hemorrhage and malignant transformation are potential complications of GSD-related hepatic adenomas. This conclusion underscores the importance of following these patients closely as they age. Nocturnal nasogastric feeding should be considered in the hope of preventing a tumor or inducing regression. Acute symptomatic attacks should be evaluated promptly for possible tumor hemorrhage.