Main principles which should be followed when choosing the strategy of treatment in patients with deformities of lower extremities are describes. The authors' experience includes 213 patients with deformities of lower extremities, 59 of them were operated upon. Basing on this experience the authors have developed a classification allowing systematization of the methods for correction of deformities of legs. The following factors were taken into account: the character and degree of the deformity, the degree of impairment of the joint functions, compensatory changes, the degree of alteration of soft tissues, patient's age and the esthetic effect estimated by the patient.