The present report concerns a child with galactosemia due to galactose-1-phosphate uridyl transferase deficiency, in whom both oral glucose and galactose tolerance tests were performed along with measurements of plasma insulin and growth hormone (GH). An oral galactose tolerance test showed an abnormally high rise and prolonged peak of the galactose curve as compared to the control. Insulin levels remained at extremely low values in both our patient and the control. GH levels showed no consistent changes in relation to blood glucose or galactose, but remained high throughout the test. GH levels showed a rise after the administration of glucose with failure of complete suppression. In the young infant, hypoglycemia may be partially prevented by hypersecretion of GH. Patients with a longer duration of untreated disease might be more prone to develop hypoglycemia.