A reproducible surgical method for the production of reduced alveolar ridge in dogs using guided tissue regeneration principles is described. 3 defects resembling a reduced ridge were formed on both sides of the mandible in 4 dogs. In each of the dogs, a polytetrafluoroethylene membrane was placed on 4 defects, while 2 defects were covered by gingival flaps only. Half of the defects were allowed to heal for 6 weeks and half for 12 weeks. Bucco-lingual width measurements revealed healing up to the membrane. In the uncovered defects, the bony wall width increased during the 12-week healing period. Histological examination showed close adaptation between bone and membrane in well-sealed defects. In cases of incomplete sealing, connective tissue had penetrated into the defect, resulting in unpredictable bone healing. The use of guided tissue regeneration techniques is suggested as a valuable tool in creating experimentally reduced ridges.