This study was undertaken to assess histologically the response to collagen based membrane materials that might be used for guided tissue regeneration (GTR) procedures, using a subcutaneous model on the dorsal surface of the rat. The commercially available materials included absorbable type I bovine collagen barrier, fascia lata, fascia temporalis and dura mater membranes. In the study 20 Wistar rats were used 80 implant materials were placed under general anaesthesia. Animals were sacrificed 7, 14, 28 and 42 days post-implantation. The specimens were assessed histologically for the composition of the tissue surrounding the membranes, the types of cells in infiltrate and the degree of resorption. It was concluded that these membrane materials were well tolerated and were gradually resorbed. Light microscopic examination showed that the type I bovine collagen and fascia lata were resorbed faster but fascia temporalis and dura mater were resorbed more slowly at 42 days. In addition the resorption process was continuing and these materials were evident histologically at 42 days.