There is described a prosthetic valve to be inserted into a body lumen, the valve having leaflets that are spread apart during forward flow of fluid to create an orifice, and the leaflets coming into contact with each other during reverse flow of fluid, thereby impeding the reverse flow of fluid, the valve comprising: a hollow, cylindrical stent having an inner surface and an outer surface, and having a first and a second open end; and valve means formed from a single tubular membrane, the membrane mounted to the stent, the membrane having a graft portion internally folded and bonded to itself at a plurality of points to form pouches such that the leaflets extend from the pouches, and a sleeve portion on an outer surface of the stent to secure the membrane thereto.