An endoluminal prosthesis system deployable in a region of a patient's vasculature having one or more branch vessels, having a main graft body having a first opening in a wall portion of the main graft body and a pre-loaded guidewire positioned inside the main graft body and advanced through the first opening. One or more branch grafts can be attached to the main graft body to cover one or more openings in the main graft body.
