Objective To summarize the effectiveness of radial dorsal fasciocutaneous flap of thumb for repairing severe nail bed defects. Methods Between May 2009 and January 2012, 16 patients with severe nail bed defect were treated with radial dorsal fasciocutaneous flap of the thumb. There were 10 males and 6 females, aged 16-54 years (mean, 36 years). The causes of injury included crush injury in 10 cases, chainsaw injury in 4 cases, and scald in 2 cases; injured fingers were thumb in 3 cases, index finger in 4 cases, middle finger in 5 cases, ring finger in 3 cases, and little finger in 1 case. The time between injury and operation was 2 hours to 8 days (mean, 19.3 hours). Of 16 patients, 9 complicated by distal phalanx fracture. The area of defect ranged from 0.9 cm × 0.6 cm to 2.3 cm × 2.1 cm. According to ZHOU Qingwen’s grading system for nail bed defects, 6 cases were rated as degree III and 10 cases as degree IV. The area of flap ranged from 1.0 cm × 0.6 cm to 2.5 cm × 2.2 cm. Retrograde transposition was performed to repair the thumb defect, and pedicled transposition to repair the 2nd-5th fingers defects. The donor sites were directly sutured or were repaired with skin graft. Results All flaps and skin grafts survived, and wounds healed by first intention. All patients were followed up 6-12 months (mean, 8 months). The color, texture, and contour of the flaps were good. According to total active motion standard, the finger function was assessed as excellent in 10 cases, good in 4 cases, and fair in 2 cases, and the excellent and good rate was 87.5%. Conclusion Radial dorsal fasciocutaneous flap of thumb is a reliable flap with easy dissection and less trauma in repair of severe nail bed defects.