Objective To investigate the cl inical results of treating leg open fracture with soft tissue defect by pedicle flap transfer in combination with external fixator. Methods From May 2004 to June 2007, 12 cases of leg open fracture with soft tissue defect, 9 males and 3 females aged 18-75 years, were treated. Among them, 8 cases were caused by traffic accidents, 2 crush, 1 fall ing and 1 mechanical accident. According to the Gustilo Classification, there were 2 cases of type II, 5 of type IIIA and 5 of type IIIB. There were 2 cases of upper-tibia fracture, 3 of middle-tibia and 7 of middle-lower. The sizes of soft tissue defect ranged from 5 cm × 3 cm to 22 cm × 10 cm.The sizes of exposed bone ranged from 3 cm × 2 cm to 6 cm × 3 cm. The course of the disease was 1-12 hours. Fracture fixation was reached by external fixators or external fixators and l imited internal fixation with Kirschner wire. The wounds with exposed tendons and bones were repaired by ipsilateral local rotation flap, sural neurocutaneous flap and saphenous nerve flap. The size of selected flap ranged from 5 cm × 4 cm to 18 cm × 12 cm. Granulation wounds were repaired by skin grafting or direct suture. Results All patients were followed up for 6 months to 2 years. All patients survived, among whom 2 with the wound edge infection and 1 with the distal necrosis were cured by changing the dressing, 8 with pin hole infection were treated by taking out the external fixator, 1 with nonunion received facture heal ing after bone graft in comminuted fracture of lower tibia, 2 suffered delayed union in middle-lower tibia fracture. The ROM of ankle in 3 cases was mildly poor with surpass-joint fixation, with plantar extension of 0-10° and plantar flexion of 10-30°, while the others had plantar extension of 10-20° and plantar flexion of 30-50°. Conclusion The method of pedicle flap transfer combined with external fixator is safe and effective for the leg open fracture with soft tissue defect.