The rigid form of static flatfeet occurs in 18 to 20% of cases of the musculoskeletal system pathology. To date, no objective diagnostic methods have been developed, no algorithms for treating the rigid form of flatfeet depending on the severity, deformity of the tarsal bones, foot mobility and dysfunction of the posterior tibialis tendon (hereinafter PTT). Objective. To develop objective evaluation methods for mobility in the joints and changes in the tarsal bones. Create algorithms for surgical treatment of rigid foot. Materials and methods. The effectiveness of the rigid form of static flatfeet treatment in 32 children (64 feet) aged 14 to 18 years, which were divided into main and control groups, was analyzed. Clinical and radiological diagnostic methods were used. Patients in the main group (15 patients) underwent surgery on bones and soft tissues.Patients in the control group (17 patients) were operated using subtalar arthroereisis method. Results. Surgical treatment was ineffective in the use of subtalar arthroereisis in cases of the tarsal bone deformity and significant impairment of foot mobility. Positive results were also achieved using two-joint arthrodesis with the formation of naviculo-tibial ligament with severe foot rigidity, stage III–IV of PTT dysfunction and navicular bone deformity. Conclusions. Treatment of rigid foot should take into account the severity, the compression ratio of the navicular bone, the mobility index, the stage of the posterior tibialis tendon dysfunction and the angle of its tension. Long-term results indicate the effectiveness of surgery on bones and soft tissues in the treatment of severe rigid flat feet. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of participating institution. The informed consent of the patient was obtained for conducting the studies. Key words: flatfeet, children, surgical treatment.