Observations on a 3-month old infant with hypoglycemia and hepatomegaly from hepatorenal glycogen storage disease are reported. The diagnosis was based on analysis of the liver as well as typical clinical and laboratory findings. The liver histologically showed accumulation of glycogen and fat and biochemically was found to be deficient in glucose-6-phosphatase. An oral galactose tolerance test resulted in lactic acidosis with failure to detect any galactose or rise in concentration of glucose in the blood. An intravenous galactose tolerance test on two occasions resulted in the normal disappearance of galactose; however the concentration of glucose remained unchanged or declined, and that of lactate rose. The intravenous galactose test offers a further means for evaluating the glycolytic pathways in the liver in glycogen storage disease.