Prevention of the alveolar bone atrophy represents one of the urgent problems in oral and maxillofacial surgery. The aim of the study was comparative evaluation of two osteoplastic bioresorbable membranes: “Collapan” made of collagen type II, hydroxyapatite and gentamycin sulphate, and “Collost” made of collagen type I for prevention of the mandible atrophy. 42 male patients aged from 45 to 70 years were involved in the clinical trial. Group 1, which was the reference group, included 20 individuals, in whom “Collapan” membrane was implanted to prevent atrophy of the alveolar bone. Group 2 included 22 patients, in whom “Collost” membrane with the same purpose was used. Clinical efficacy was assessed by analysis of the number of complications in the postoperative period. The level of the alveolar bone atrophy was assessed at the long-term follow-up (after 1 year) based on the parameters of the mandibular bone tissue determined by cone-beam computed tomography. In the postoperative period in the group 1 there were revealed 6 (14%) cases of infectious-inflammatory complications – alveolitis, 2 (5%) of them were revealed after the third molar atypical removal and 4 (9%) after a complicated extraction of the tooth. In group 2 – 2 (5%) complications were reviled: 1 (2.5%) - alveolitis and 1 (2.5%) - forced tooth extraction. The use of the “Collost” membrane allowed maintaining the height of the alveolar bone in patients during the observation period. The results obtained in the trial allow us to conclude that the use of the osteoplastic bioresorbable membrane “Collost” is most appropriate for prevention of the alveolar part of the lower jaw atrophy.