Abstract: A vascular prosthesis delivery system comprises a radially self expandable vascular prosthesis and a delivery sheath with a lumen with a smaller diameter storage region and a larger diameter delivery region. A prosthesis is housed within the storage region and is movable into the delivery region for delivery at a target site within a patient. The delivery force required to move the prosthesis from the delivery region into the patient can be less than the force required to move the prosthesis from the storage region into the delivery region. In some examples, the storage region defines a tapered lumen expanding in diameter in a distal direction. In some examples, the storage and delivery regions are generally coextensive and define a tapered lumen expanding in diameter in a distal direction. A method stores a vascular prosthesis in the storage region and delivers it to a target site from the delivery region.