Impaired oral (OGTT) and i.v. glucose tolerance (IVGTT) has been found in some women receiving oral contraceptives (Wynn & Doar, 1966). The precise cause is not known but it has been suggested that elevated plasma growth hormone (GH) levels may be responsible (Spellacy, Carlson & Schade, 1967). Striking increases of OGTT and IVGTT blood pyruvate levels have also been found during oral contraceptive therapy (Wynn & Doar, 1966). The present study was undertaken to investigate the acute effects of GH on carbohydrate and intermediary metabolism. Two IVGTT's were carried out by methods previously described (Wynn & Doar, 1966) in 12 normal ambulatory subjects (aged 20–49), six of whom were women. The first test served as a control. The second test was carried out 120 min. after i.v. administration of 5 mg. human GH (HGH, MRC R. 10 Batch). Blood samples were analysed for plasma glucose (Cramp, 1967), non-esterified fatty acid