ObjectiveTo investigate the effectiveness of part long thumb extensor tendon dorsal ulnar artery chimeric flap for repair of Doyle type Ⅲ mallet finger of thumb. MethodsBetween June 2013 and April 2015, 9 cases of Doyle type Ⅲ mallet finger of thumb were treated, which were caused by planer injury. There were 6 males and 3 females, aged from 15 to 65 years (mean, 36 years). The time from injury to operation was 3-8 hours (mean, 5 hours). All cases had interphalangeal joint dorsal skin and soft tissue defects of the thumb; the skin defects ranged from 2.0 cm×1.5 cm to 2.3 cm×2.3 cm; the extensor tendon defect ranged from 0.5 to 1.5 cm in length (mean, 1.0 cm). The part long thumb extensor tendon dorsal ulnar artery chimeric flap of 3.0 cm×2.5 cm to 3.5 cm×3.0 cm in size was used to reconstruct extensor tendon and wound. The donor site was repaired with nasopharyngeal fossa perforating branches pedicled V-Y relay flap. ResultsAll flaps survived completely and incisions healed by first intention. All patients were followed up 4-12 months (mean, 6 months). The flaps had good color, texture, and contour. At 6 months after operation, the two-point discrimination of chimeric flap was 10-12 mm (mean, 11 mm), and two-point discrimination of relay flap was 12-14 mm (mean, 13 mm). The interphalangeal joint flexion of thumb was 0-40°, and the thumb opposition function was normal. ConclusionPart long thumb extensor tendon dorsal ulnar artery chimeric flap can repair the Doyle type Ⅲ mallet finger of thumb, which has no injury to the artery and nerve. At the same time the relay flap can achieve linear healing, so good appearance and function of the thumb can be obtained.