Background Sural neurofasciocutaneous flap has been popularly used as an excellent option for the coverage of soft tissue defects in the lower third of leg, ankle and foot, but its free transplantation has been rarely reported. The objective of our work was to investigate the operative technique and clinical results of repairing the soft tissue defects of hand and forearm with free peroneal perforator-based sural neurofasciocutaneous flap. Methods Between May 2006 and March 2007, 10 patients including 7 men and 3 women were treated. Their ages ranged from 22 to 51 years. They presented to emergency with large soft tissue defects of 16 cm × 7 cm to 24 cm × 10 cm in size in hand and forearm after injured by motor vehicle accidents (2 cases) or crushed by machine (8 cases). Thorough debridements and primary treatments to associated tendon ruptures or bone fractures were performed on emergency. And free peroneal perforator-based sural neurofasciocutaneous flaps were transplanted when the wound areas were stable at 5 to 7 days after emergency treatment. The flaps were designed along the axis of the sural nerve according to the shape and size of the soft tissue defects, with the peroneal perforator above the lateral malleolus as the pedicle and along with a part of the peroneal artery for vascular anastomosis. Then the flaps were harvested to repair the recipient sites with the pereneal artery anastomosed to the radial (or ulnar) artery and the peroneal veins to one of the radial (or ulnar) veins and the cephalic vein respectively. The flap sizes ranged from 18 cm × 8 cm to 25 cm × 12 cm. The donor areas were closed by skin grafts. Results All of the 10 flaps survived after surgeries. Marginal necrosis occurred in only 2 cases. The skin grafts survived entirely in the donor sites, and no obvious influence on the donor legs was observed. All of the transplanted flaps presented favourable contours and good functions at 9 to 12 months' follow-up. Conclusions Peroneal perforator-based sural neurofasciocutaneous flap has favourable appearance, constant vascular pedicle, reliable blood supply, large size of elevation, and minimal influence on the donor site. The free transplantation of this flap offers a satisfactory alternative for repairing the large soft tissue defects of forearm and hand.