Guided tissue regeneration (GTR) membranes with bioabsorbable characteristics have been employed, in recent years, for periodontal procedures to deflect the growth of gingival tissues away from root surface. They provide an isolated space over regions with defective tissues and allow the relatively slow growing periodontal ligament fibroblasts to be repopulated over the root surface. In this study, we have employed chitosan and tricalcium phosphate (beta-TCP) as viable membrane materials and evaluated their roles in GTR applications. Three types of beta-TCP/chitosan membranes, weight ratio of beta-TCP/chitosan 65 : 35, 33 : 67, and 10 : 90, were prepared for three categories: the mechanical strength to create an effective space; the rapid rate to reach hydrolytic equilibrium in phosphate buffer solution; and the ease of clinical manipulations. Consequently, standardized, transosseous, and critical-sized (cavity of 8 mm) skull defects were made in adult rabbits, and the defective regions were covered with the specifically prepared chitosan membranes. After 4 weeks of recovering, varying degrees of bone healing were observed beneath the beta-TCP/chitosan membranes in comparison to the control group. The beta-TCP/chitosan membranes covered regions showed a clear boundary space between connective tissues and bony tissues. Over all, good cell-occlusion and beneficial osteogensis effects by these bioabsorbable materials toward the wound recovery were indicated. (c) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 3127-3134, 2009