Since Sir Astley Cooper's1 first description of the lesion in 1842, the literature has been replete with reports of frank dislocations at the lower radio-ulnar articulation associated with Colles' fracture. The more frequent but less severe degrees of relaxation in that joint, however, have received scant attention. In approximately one of every nine cases, Colles' fracture is followed after the healing period by laxity of the radio-ulnar joint. In some of these instances slight radio-ulnar diastasis is present, causing broadening of the wrist and apparent radial deviation of the hand. In others, the bones remain loosely in their normal position, and no deformity is apparent. In some cases the condition is entirely symptomless. In many, however, its association with lasting weakness, limitation of rotation and pain in the ulnar aspect of the wrist joint is of sufficient regularity to indicate a causal relationship which merits investigation. Many observers have