A case of late post-traumatic dislocation of the ring and little finger carpometacarpal joints is described. An avulsion fracture from the base of the ring finger metacarpal was noted, but normal alignment was demonstrated by radiographs in the acute postinjury period. However, 3 months repeat radiographs showed a fixed dorsal dislocation. Although late spontaneous carpometacarpal dislocations are rarely encountered, they may develop following an untreated injury that disrupts the ligamentous stability of the joint. Therefore, an index of suspicion should exist for this possibility. The patient described here had pain and decreased grip strength and, therefore, treatment with open reduction and internal fixation was recommended. At the patient's follow-up examination, his pain has resolved and he had normal motion and grip strength. This treatment is advised when the articular cartilage of the carpometacarpal joint surface has been preserved, although sufficient cast immobilization when the avulsion fracture was initially noticed might have prevented the late dislocation.