Forty patients with Galeazzi fracture-dislocations were treated with open reduction and internal fixation of the radial shaft fracture. Intraoperative distal radioulnar joint (DRUJ) instability after anatomic reduction was managed with supplemental wire transfixion of the DRUJ (10 patients) or open reduction and triangular fibrocartilage complex repair (3 patients). Two patterns of fracture-dislocation were identified based on the location of the radial shaft fracture. Twenty-two type I fractures were in the distal third of the radius within 7.5 cm of the midarticular surface of the distal radius; 12 of these cases were associated with intraoperative DRUJ instability. Eighteen type II fractures were in the middle third of the radial shaft more than 7.5 cm from the midarticular surface of the distal radius. Only one of these fractures had intraoperative DRUJ instability after open reduction and internal fixation of the radial shaft fracture. A high index of suspicion, early recognition, and acute treatment of DRUJ instability will avoid chronic problems in this complex injury.