A fenestrated graft deployment system, with a delivery catheter having a catheter body, An endoluminal prosthesis having a main graft body, the main graft body having a lumen therethrough and a first opening laterally through a wall of the main graft body. A first guidewire prepositioned within the delivery catheter extending through at least a portion of the catheter body into a main lumen of the endoluminal prosthesis and through the first opening in the wall of the prosthesis when the delivery catheter is in a predeployed configuration. A first fenestration alignment device is configured to extend through at least a portion of the delivery catheter and is configured to be axially moveable relative to the first guidewire. The first fenestration alignment device has an end portion having an outside perimeter configured such that when an end portion of the fenestration alignment device moves toward the first opening of said main graft body the outside perimeter of the first opening is smaller than the outside perimeter of the first fenestration alignment device and prevents it from passing through the first opening and causes the main graft body adjacent to the first opening to move with the end of the first fenestration alignment device to act as alignment tool to allow an operator to align the first opening in the side of the endoluminal prosthesis with an ostium of a target branch vessel into which said first opening is to extend and act as a guide and seal for a subsequently delivered branch graft endoluminal prosthesis.
