Recent studies suggest possible deleterious effects of chronic exposure to certain common anesthetic agents. A simple and economic gas evacuator was designed with an "angle stop valve" of a water pipc system which was easily purchased from a hardware store. The device was installed as follows: 1) The pop-off valve assembly of an Ohio Unitrol anesthesia machine was removed and replaced with atail-piece of an angle stop valve with a new screw which was made to fit in place. 2) The disk of the angle stop valve was fixed in place with adhesive cement. 3) The tail nut and tail packing of the angle stop valve were replaced with the same caliver long vinyl hose, which eliminated overflow anesthetic gases from the anesthesia machine air vent system of the operating room. This device is inexpensive and simple to operate and is being used successfully in routine clinical practice.