In this retrospective study of 96 Mitchell first-metatarsal osteotomies performed on 69 patients with an average follow-up of 7 years, we found that more than 86% were completely satisfied and that the procedure was equally effective in all age groups. Excessive first metatarsal shortening, dorsiflexion of the osteotomy, and failure to correct the intermetatarsal angle to 10 degrees or less correlated with poorer results. This study demonstrates a relationship between metatarsal shortening and osteotomy plantarflexion. Gait analysis demonstrated that these patients do not have normal foot mechanics postoperatively.