Abstract: An anesthesia induction chamber for small animals having a chamber defined by a bottom wall, a pair of opposing side walls, a front end wall, a rear door mounted on a hinge, and a top cover attached to a side wall by an elongated piano hinge. The walls, rear door and top cover are impermeable to gases. The front end wall has a gas inlet port to which a gas source, such as an anesthesia machine, may be attached. The rear door includes a vent port which is adapted to receive a scavenger or other device for removing carbon dioxide or other gaseous waste from the chamber. The chamber has a first partition wall disposed to slide through one of the side walls adjacent the rear door so that a small animal may enter the chamber through the open rear door and subsequently be confined in the chamber by sliding the first partition wall closed. A second partition wall may be inserted to reduce the size of the chamber.