A disposable air/water valve for an endoscope, including a shaft having a passage from an opening to a vent. The shaft has grooves and ridges and a protrusion formed at the vent. Seals are set within some of the grooves. An inner ring, having a diaphragm, extends from an outer circumference of the inner ring to an internal circumference of an outer cap. Hinges extend vertically downward from the diaphragm and ribs are formed along the internal circumference of the outer cap. A button cap has an internal ring that securely attaches to the shaft. A resilient member is securely disposed between the button cap and the diaphragm. The outer cap, inner ring, and internal ring of the button cap define a central bore to accommodate the shaft therein.