Objective To investigate the therapeutic effect of repairing postoperative soft tissue defects of tibia and ankle open fractures with muscle flap pedicled with medial half of soleus. Methods From February 1998 to January 2009, 15male patients with postoperative soft tissue defects of internal fixation for tibia and ankle open fractures were treated. Their age was 18-54 years old (average 32 years old). The injury was caused by traffic accident in 13 cases and hit of heavy objects in 2 cases. The injury was in the left side in 9 cases and the right side in 6 cases. The soft tissue was necrotic and combined with purulent secretion. All patients presented with exposure of bone and steel plate. The soft tissue defect was located on the upper-segment of tibia in 2 cases, the middle and lower-segments of tibia in 9 cases, and the ankle in 4 cases. The size of the defect was 5 cm × 4 cm- 13 cm × 6 cm. The time from the internal fixation to the operation was 3-6 months (average 4 months). The method of anterograde transposition of muscle flap pedicled with medial half of soleus was used to repair the defects in 2 cases, and the method of retrograde transposition was appl ied to repair the defects in 13 cases. The muscle flap harvested during operation was 5 cm × 4 cm- 13 cm × 5 cm in size. The muscle flap was covered with spl it thickness skin graft (2.5 cm × 1.5 cm-10.0 cm × 5.0 cm) of femoribusinternus in 14 cases, and island flap with nutritional vessel pedicle of sural nerve (7 cm × 6 cm) in 1 case. Results One case had skin graft necrosis 5 days after operation and healed after re-debridement, vacuum seal ing drainage, and dermatoplasty. For the rest 14 patients, the incision all healed by first intention, and the skin graft, skin flaps, and muscle flaps were all survived. All wounds of the donor sites healed by first intention. Thirteen patients were followed up for 6 months to 8 years (average 3 years). The grafted skin presented with good wearabil ity and without ulceration and overstaffed appearance. At the final follow-up, the activity range of ankle was 5-10° in extension and 10-15° in flexion, and the gait was abnormal. Conclusion Muscle flap pedicled with medial half of soleus transposition is easy to be operated with a big rotating arc, can fill the narrow cavity and repair the soft tissue defect simultaneously, and provide flat and non-bloated postoperative incision with minor donor-site injury. It is one of the effective methods of repairing the postoperative soft tissue defect after internal fixation of tibia and ankle open fractures.