Two varieties of collagen/sodium hyaluronan membranes were used as dermal substitutes in a biocompatibility implantation study on rats. In order to improve especially the physical and mechanical properties of the material, the membranes were chemically modified using a combination of hexamethylenediisocyanate (HMDC) as a crosslinker and polyoxy-ethylene (POE) as a spacer. According to both macroscopic and microscopic histological observations, the membranes were well accepted by the surrounding host tissue in all the animals. No major differences in relation to the outgrowth of the material by host tissue have been observed between the implant varieties A and B. The most important finding was that no pathological changes or important alterations of the host tissues were detected.