The effect of hormone replacement therapy on carbohydrate metabolism in menopausal women is briefly reviewed. Estrogen treatment has bi-phasic effect; abnormal glucose tolerance with a normal insulin level is commonly found within 3 months of treatment, followed by normalization of the glycemia when treatment is extended beyond one year. Normal tolerance usually occurs once treatment is stopped. Estrogens may therefore be regarded as being glucogenic (reversible blood glucose elevation) rather than diabetogenic (permanent hyperglycemia). With some exceptions, progestogens have little effect on glucose tolerance within the first 3-6 months of treatment; thereafter progressive hyperglycemia and hyperinsulinemia occur. Postulated mechanisms for the hormonal effect on carbohydrate metabolism are noted, including the possible synergistic effect of estrogens on progestogen glucogenic activity. The significance of chronic hyperglycemia and vascular disease is commented upon.