Abstract: A biopsy valve includes a body having a first groove adapted to fit over a lip of an endoscope working channel and a second groove and a first membrane. A primary cap is mechanically coupled to the body by a primary strap extending between the primary cap and the body. The primary cap includes a primary cap lip to couple into the second groove of the body, a second membrane and a primary cap groove. A guard cap is mechanically coupled to the body by a guard cap strap extending between the guard cap and the body. The guard cap includes a guard cap lip which couples into the primary cap groove of the primary cap, and a third membrane. A triple membrane biopsy valve and a method of using a biopsy valve with an endoscope working channel are also described.