A tubular prosthesis including a tubular wall portion of loosely interlocked pattern, e.g. of knitted loops, constructed to function within a body lumen. The loops are preferably formed of co-knitted strand materials. A first strand material is a metal strand that structurally defines the tubular shape of the prosthesis and maintains the shape when positioned in the lumen. A second strand material is a predetermined substance selected to provide desired characteristics to the wall of the prosthesis.