External fixators are popular in treatment of the open fractures of long bones, especially tibia, associated with soft tissue injury, because they prevent further injury to the injured soft tissue and bone. Over the past ten years, bilateral frame external fixtors such as Hoffmann system had been used for lower extremity lesions. But they had many disadvantages like that bilateral frames were less rigid in A-P plane bending moment mechanically, therefore unilateral frame external fixators such as Monofixateur have been introduced recently. The Monofixateur was able to fix the fracture rigidly and compress, distract and neutralize the fracture site and could be used as a static and dynamic stabilizer. We have treated 19 cases using Monofixateur of the Gotzen type for open fractures of lower extremity from October 1984 to Febrary 1987. The summary of the results obtainained from this study are as follows : 1. Monofixateur was easy to use, simple and light. It provided a rigid stability to fracture. 2. It was possible to allow static stabilization on the unstable fracture, whereas dynamic stabilization on the stable fracture. 3. Application was easier than any other type of external fixators from the view point of using a few screws and unilateral frame, therefore it could prevent further soft tissue injury and was easy to secondary operation. 4. It was possible to use for short fracture fragment of the proximal or distal fractures of the long bone. 5. The fracture healing time averaged 32.5 weeks and there were marked differences of the fracture healing time between open type I, II and III fractures. 6. There was little complication such as pin tract infection and ankylosis of the joint.