Abstract： Objective:To investigate the clinical efficacy of free transplantation of the second toenail flap for repairing composite tissue defects in the distal segment of fingers (excluding the thumb) with bone, nail bed, and pulp defects.Methods:From September 2019 to September 2022, 10 patients (10 fingers) with composite tissue defects in the distal segment of fingers accompanied by bone, nail bed, and pulp defects were treated. Free second toenail flap was used to repair partial composite tissue defects in the fingers.Results:All 10 cases of the second toenail flap survived after surgery, and the wounds in the donor and recipient areas achieved primary healing without any complications. One case showed slight swelling of the flap after surgery, and a secondary modified flap thinning surgery was performed. The follow-up time was 6 to 24 months, with an average of 13 months. The appearance of the fingers was close to normal, the fingertips were full with fingerprints, good texture, and the skin flap color was not different from normal. The two-point discrimination was 4 to 8 mm, with an average of 6.5 mm. The nails were flat and had a good appearance. The Vancouver Scar Scale (VSS) was used to evaluate the scars in the finger and foot donor areas. The average VSS score for finger scars was 0.5 points, and the average VSS score for donor area scars was 1.5 points. In all cases, the finger flexion and extension function were normal, and the foot donor area walking, running and jumping functions were normal. According to the comprehensive evaluation criteria of the thumb and finger reconstruction function evaluation of the Chinese Society of Hand Surgery, 9 cases were excellent, and 1 case was good.Conclusion:Free second toenail flap transplantation has achieved ideal results in repairing composite tissue defects in the distal segment of the finger. Although the surgical risk is high, the success rate and patient benefit rate are acceptable. Without damaging the first toe, the reconstructed fingernail and pulp have a relatively beautiful appearance, fingerprints, good sensation, and minimal trauma to the donor area. It not only reconstructs and restores hand function, but also achieves good cosmetic effects, reduces patient psychological pressure, and has important clinical significance.