Abstract: A wheelchair seat for placement in a foldable wheelchair frame in which a rigid, substantially flat seat base operable to be received by a wheelchair frame has an elongated opening coaxial with the major axis of the perineum of a person when normally seated on the seat base and of such minimal dimensions as to permit the normally free passage of excretions through the opening without detracting from the support provided by the seat base; an elongated arm member pivotably mounted on the underside of the seat base for rotation about an axis perpendicular to its major plane; an elongated gate of a length and a width sufficient to occlude the opening, a gate stop disposed on the bottom of the seat base; and a removable waste receptacle support disposed on the seat base beneath the opening.