Many papers dealing with the clinical use of ketobemidone (Cliradon, Ciba) have called attention to the low potentiality for addiction of this drug. Studies based on large series of cases have shown that patients can give up its use without particular difficulty (Lewis, 1949; Cecchi, 1950; Blanke, 1950; Liessem, 1951; Peltola, 1952). Thus, in spite of fairly extensive use, comparatively few cases of addiction to ketobemidone have been brought to notice. Only in Germany, where the sale of the drug was unrestricted until 1953, has there been a significant number of addicts. There are reports on 20 cases in Germany either of addiction or of misuse (Linder and Vollmar, 1950; Bernmeier and Heine, 1950; Sattes, 1951; Kinzler, 1952; Mühlau, 1952; Cieslak, 1952; Hamburger, 1952; Geller, 1952; Carrière, 1953) and on 4 cases in other parts of the world (Bernstein, 1949; Del Bono, 1952; Peltola, 1952). We may assume, however, that