This invention relates to a method for preparation of a tissue graft composition from a segment of small intestine. A tissue graft composition is described which comprises the tunica submucosa of a segment of small intestine of a warm-blooded vertebrate wherein the tunica submucosa is delaminated from the tunica muscularis and at least the luminal portion of the tunica mucosa. The tissue graft composition has been shown to have excellent mechanical characteristics, as well as non-allergenicity and non-thrombogenicity in applications as vascular autografts, vascular allografts, and vascular heterografts.
