PURPOSE: Stiffness in the first metatarsophalangeal joint after surgery for hallux valgus has been reported. The goal of this study was to test the efficacy of releasing plantar aponeurosis for improving the range of extension in the first metatarsophalangeal joint that was limited after hallux valgus surgery. MATERIALS AND METHODS: Thirteen patients (1 man, 12 women [17 feet]; median age, 54.4 years; range, 44~69 years) with limited first metatarsophalangeal joint extension after hallux valgus surgery, who underwent an additional procedure of plantar aponeurosis release between March 2015 and August 2015, were included. Subsequently, the passive range of extension in the first metatarsophalangeal joint was evaluated via knee extension and flexion positions. Hallux valgus angle, inter-metatarsal angle, distal metatarsal articular angle, and talo-first metatarsal angle were measured on weightbearing dorsoplantar and lateral radiographs of the foot preoperatively. RESULTS: The mean range of extension for the first metatarsophalangeal joint improved significantly, from 2.5° to 40.9° in the knee extension position (p<0.00). The mean extension range for the first metatarsophalangeal joint also improved, from 18.2° to 43.2° in the knee flexion position (p<0.00). In all patients, congruence of the first metatarsophalangeal joint was recovered. CONCLUSION: Plantar aponeurosis release is an effective additional procedure for improving the extension range of the first metatarsophalangeal joint after hallux valgus surgery.