A new valgus brace was evaluated in 15 patients with medial osteoarthritis of the knee and a varus leg axis. Significant improvement of pain and function were found after 6 weeks of brace treatment. Gait analysis showed that the brace had a tendency of lowering the peak varus moment about the knee. This effect was more profound in the presence of higher initial varus deformity angle of the knee. Furthermore, bracing led to a small decrease of knee extension at the end of the swing phase and an increase of walking velocity. The mechanisms identified by gait analysis in this study may be of clinical importance for future developments in brace treatment.