A study has been made of the effect of hypernatremia on carbohydrate metabolism in the rat. It was shown that rats rendered hypernatremic by subcutaneous injections of hypertonie sodium solutions manifest increased fasting blood glucose levels, as well as a decreased ability to dispose of an exogenous glucose load. The mechanism by which hypernatremia alters carbohydrate metabolism has not been determined. However, an impairment of normal cellular functions known to accompany hypertonicity of body fluids as well as disturbed secretion of the hormones which regulate carbohydrate metabolism, could explain the metabolic abnormality.