A resorbable collagen membrane for use in guided tissue regeneration, comprising a substantially purified collagen membrane which is physiologically acceptable for implant into a mammalian body and which is derived from a natural collagen membrane so as substantially to retain the native collagen structure one face of the membrane is fibrous so as to allow cell growth thereon, whilst the opposite face is smooth so as to act as a barrier and prevent passage of cells therethrough. Such a membrane is particularly useful in treatment if wounds and lesions.
