Patients with Colles' fractures have serious complications more frequently than is generally appreciated. A study of 565 fractures revealed 177 (31 per cent) with such complications as persistent neuropathies of the median, ulnar, or radial nerves (forty-five cases), radiocarpal or radio-ulnar arthrosis (thirty-seven cases), and malposition-malunion (thirty cases). Other complications included tendon ruptures (seven), unrecognized associated injuries (twelve), Volkmann's ischemia (four cases), finger stiffness (nine cases), and shoulder-hand syndrome (twenty cases). In many patients, incomplete restoration of radial length or secondary loss of the reduction position caused the complications.