Choline chloride was administered orally (3 to 15 gm per day) to five patients with Huntington chorea. A long-lasting dose-dependent elevation of the concentration of free choline in plasma was obtained and the highest plasma concentrations (25 to 30 mumol per liter) were of the same magnitude as those that increase brain acetylcholine content in the rat. However, the choline treatment did not conclusively alter the involuntary movements of these patients.