Abstract: Objective To observe the effect of expanded lateral thoracic abdominal flap transferred with pedicle on repairing large area of hypertrophic scar after burn of the upper extremity. Methods Twelve patients with large area of secondary hypertrophic scar 8 month to 3 years after healing of burn wound on the upper extremity were hospitalized in Zhengzhou First People′s Hospital from October 2008 to October 2015, with scar area ranging from 11 cm×7 cm to 20 cm×10 cm. Five patients were with limited straightening and bending of elbow. The scars were reconstructed with ipsilateral expanded lateral thoracic abdominal flap or that combined with expanded upper extremity flap according to the area of scar. Lateral thoracic abdominal incision was located near the anterior axillary line, and upper extremity incision was located near scar edge. A capsule cavity was formed by blunt dissection in the superficial fascia layer. Expander with suitable capacity was implanted with the injection pot being built-in. Volume of water reaching 1 time to 3 times of the capacity of expander was injected for excessive expanding. The expanded lateral thoracic abdominal flap supplied by lateral thoracic cutaneous artery and expanded upper extremity flap were dissected after the completion of expanding. The expanded upper extremity flap was advanced locally to cover the surrounding secondary wound after resection of hypertrophic scar. The expanded lateral thoracic abdominal flap was transferred with pedicle to reconstruct scar, with pedicle being sutured in skin tube-like shape, and the flap donor site was sutured directly. Flap pedicle separation was carried out 3 weeks after surgery. Anti-scar treatment was carried out after healing of sutured area. Results Totally 18 expanders were implanted, without complications such as infection, exposure of expander, and so on. The areas of expanded lateral thoracic abdominal flaps were from 11 cm×7 cm to 16 cm×11 cm. The combined application of expanded upper extremity flaps with area ranging from 8 cm×4 cm to 9 cm×6 cm was used in 6 patients. All the flaps survived with incision healed. The color, texture, and thickness of skin area repaired by flap were close to those of the normal skin of upper extremity after 6 months to 2 years′ follow-up afer discharge. The limited straightening and bending of elbow in 5 patients were rectified. Obvious linear scar was observed in the sutured area of surgery in 3 patients, while light linear scar was observed in the sutured area of surgery in 9 patients. Conclusions Expanded lateral thoracic abdominal flap has constant blood vessel and is easy to be dissected. It can achieve well reconstruction of appearance and function in repairing large area of hypertrophic scar after burn of the upper extremity.