Abstract: A carbon dioxide absorption canister is used with a closed circuit or circle analgesia apparatus, including a gas supply machine, a face mask for the patient, and inhalation and exhalation conduits. The carbon dioxide absorption canister is operatively coupled to both the gas supply machine and the face mask. The canister is composed of a container having a cylindrically shaped side wall with an integral bottom and a removable lid. Both the container and the lid are composed of a synthetic, transparent, resinous material such as an acrylic resin. The gas inlet from the patient to the canister is located at the bottom and contains a check valve that allows flow only into the canister through the inlet. An absorption medium support tray, positioned in the container and spaced above the bottom of the container, supports a quantity of absorption medium, such as soda lime.