To the Editor: An interesting report in the Journal by Weissman, Shenkman and Gregerman (N Engl J Med 284: 65–71, 1971) suggested that chlorpropamide therapy in diabetic patients could lead to serious hyponatremia on the basis of its antidiuretic activity (probably by potentiating the antidiuretic hormone). Five such patients were described, and a further three were found among 80 clinic subjects. We have measured the serum sodium levels in 406 patients with maturity-onset diabetes taking oral hypoglycemic drugs attending the Groote Schuur Hospital Diabetes Clinic, of whom 221 were on chlorpropamide, mostly 500 mg per day. In none was the. No extract is available for articles shorter than 400 words.