PURPOSE: The purpose of this study was to evaluate the effect and short-term results of the modified Mau osteotomy designed by the author. MATERIALS AND METHODS: Seventeen feet treated with newly designed osteotomy from 2003 to 2004 were included. We performed metatarsal osteotomy and distal soft tissue procedure on 17 feet (12 patients) and additional Akin osteotomy on 6 feet (4 patients). An oblique osteotomy was made from the neck in the dorsum, aiming proximal to the base of the first metatarsal with vertical short arm on the base. We performed long arm of osteotomy parellel to the acrylic plate which was supposed as ground plane. Preoperative radiographs and follow up radiographs at three month were used for radiologic evaluation. RESULTS: Mean hallux valgus angle was 43.6 degrees and mean intermetatarsal angle was 20.4 degrees on preoperative weight bearing radiograph. Mean amount of correction of the hallux valgus angle was 37.5 degrees and intermetatarsal angle was 14.2 degrees at three months after operation. There was no fixation loss or malunion, and the clinical result was subjectively exellent. CONCLUSION: More proximal rotational axis can achieve sufficient intermetatarsal angle correction, and vertical arm can provide more stable contact. So this newly modified Mau osteotomy was considered as a good alternative procedure in the treatment of severe hallux valgus.