The ball-joint fixator is a one-plane external fixator system that allows correction of the reduction postoperatively. Dynamic axial loading is made possible by a telescoping device. Between January 1987 and June 1991, 312 external fixators were applied in the Department of Trauma of the Surgical University Clinic in Freiburg/Breisgau. In 25 of these cases the ball-joint fixator (Unifix) was used. The study includes 16 open and 8 closed tibial fractures and 1 open femoral fracture. The pin-tract infection rate was 14%. In 16 patients a cast was necessary for a short time after the fixator had been removed, and 3 other patients needed intramedullary nailing. The long-term complications observed were osteitis pseudarthrosis and refracture (in 1 case each). The ball-joint fixator is a device that can be applied very easily and quickly. It can be used to advantage in the treatment of multiple trauma patients with open tibial fractures. Because of the fixed distance between the pin clamps there is no advantage over the original AO fixator in fractures where the telescoping mechanism cannot be used.