Purpose: The aim of this study was to evaluate the behavior of a demineralized bone matrix membrane and a polytetrafluoroethylene (PTFE) membrane in the process of bone repair of surgical defects filled with autogenous bone in rats. Materials and Methods: Sixty rats weighing approximately 250 g each were selected and separated into three groups: control group without membrane, demineralized bone matrix membrane group, and PTFE membrane group. Bilaterally, surgical defects of 2 mm in diameter were prepared in the tibiae. The defect in the left tibia was filled with particulate autogenous bone collected during the creation of the two defects and was left uncovered (control) or was covered with the membranes investigated by the present study. At 10 or 60 days postoperatively, the rats were euthanized and the left tibiae were submitted to routine laboratory processing for histomorphometric analysis. All groups were evaluated separately on the 10th and 60th days after surgery. The Kruskal-Wallis test was used for group comparison. Results: The membrane-treated defects showed a delay in healing. Sites treated with demineralized bone matrix membrane showed, as early as day 10, more newly formed bone and slow replacement until day 60. At day 60, the sites covered with demineralized bone matrix membrane and with synthetic membrane showed statistically significant results. Conclusion: The demineralized bone matrix membrane proved to be biocompatible. In terms of newly formed bone area, both membranes showed similar performance. Keywords: autologous transplantation, guided tissue regeneration, homologous transplantation