Purpose: The aim of this study was to examine the effects of laterally wedged insoles to treat knee osteoarthritis on frontal plane mechanics and knee varus moment after one year. Methods: Fourteen individuals diagnosed as having medial knee osteoarthritis (OA) and 13 healthy controls were included in this study. Patients wore bilateral full length laterally wedged insoles with medial longitudinal arch, made of high density ethyl vinyl acetate, with 5 degrees tilt angle in their shoes on a regular basis for at least one year. Three dimensional kinematics and kinetics were recorded as the knee OA patients walked in the laboratory after nearly one year both barefoot and with their insoles. Results: Knee angles and total range of motion in the frontal plane were not significantly different between walking conditions when compared to control group (p>0.05). Walking speed and step width were similar when patients walked barefoot and with laterally wedged insoles (p>0.05). Knee varus moment was prominently high when walking barefoot, and significantly decreased with laterally wedged insoles (p<0.05). Conclusion: Our data suggests that use of 5 degrees laterally wedged insole have significant effects on knee varus moment in knee OA.