Background. The sensomotor insole (SMI) has clinically been shown to be successful in treating an intoeing gait. We investigated the biomechanical effect of SMI on a pediatric intoeing gait by using three-dimensional gait analysis. Methods. Six patients with congenital clubfeet and four patients with idiopathic intoeing gait were included. There were five boys and five girls with the average age at testing of 5.6 years. The torsional profile of the lower limb was assessed clinically. Three-dimensional gait analysis was performed in the same shoes with and without SMI. Results. All clubfeet patients exhibited metatarsal adductus, while excessive femoral anteversion and/or internal tibial torsion was found in patients with idiopathic intoeing gait. SMI showed significant decreased internal rotation of the proximal femur in terminal swing phase and loading response phase. The internal rotation of the tibia was significantly smaller in mid stance phase and terminal stance phase by SMI. In addition, SMI significantly increased the walking speed and the step length. Conclusions. SMI improved abnormal gait patterns of pediatric intoeing gait by decreasing femoral internal rotation through the end of the swing phase and the beginning of the stance phase and by decreasing tibial internal rotation during the stance phase.