Described herein are methods of preparing human amniotic membrane tissue grafts derived from the placenta. The grafts are composed of three layers as seen in the amniotic membrane in utero. These grafts are processed using physiologic solutions, lyophilized and terminal sterilized (via gamma irradiation in a frozen state) that thereby preserves the graft in such a manner as to retain the naturally occurring biological properties of the amniotic membrane and offer a sterile graft for transplantation. By dehydration via lyophilization and terminal sterilization in a frozen state, the graft has the advantage of storage at ambient temperatures for prolonged periods of time prior to transplantation.