An endoprosthesis that can be percutaneously implanted by means of a catheter in a patient's body, especially inside a blood vessel or other body cavity. The endoprosthesis is oblong and hollow. It can be expanded once properly implanted to fit the lumen of the vessel or cavity. It comprises a sleeve surrounding at least the outside of a skeleton. The sleeve and the skeleton are initially narrow enough to be implanted and expand once they have been implanted. Room is left between the outer surface of the sleeve of the implanted endoprosthesis and the inner surface of the vessel or cavity it is implanted in. Drugs or other substances can be delivered to the room through at least one length of flexible tubing communicating with the sleeve. The sleeve can have spacers projecting radially out of it. The sleeve can also be a hollow membrane with the flexible tubing communicating with it. The sleeve is wrapped around the skeleton, leaving wrinkles and folds.