Chronic recurrent volar dislocation of the distal radioulnar joint is a rare condition for which many operative procedures have been described. We describe a case of painful dislocation on supination. Investigation of the distal radioulnar joint revealed the absence of degenerative arthritis and a flat sigmoid notch that permitted dislocation. The case was successfully treated by osteoplasty of the volar lip of the sigmoid notch to create a buttress that prevented volar dislocation. (J Hand Surg 2001;26A:454-459.