A method of using a substantially non-porous equine collagen foil to repair and regenerate dura mater tissue of mammals when the dura mater tissue is damaged as a result of injury, tumors, surgery, and the like. The non-porous equine collagen foil comprises collagen fibrils which provides a replacement dura mater composition that is elastic, liquid-tight, and which has a high tensile strength. The non-porous equine collagen foil is furthermore resorbable and provides a biomatrix, wherein a neodura is rapidly formed which becomes indistinguishable from the autologous dura mater in a matter of weeks. The process for making the equine collagen foil reduces the likelihood of disease transmission.