Abstract: A seat for a collapsible invalid wheelchair comprising: a flexible padded seat; an elongated, generally rectangular opening in the seat; reinforcing means located within the seat and at the underside of the seat respectively on either side of the said opening; flanges on the underside of the seat; a removable waste-receiving receptacle sliding in said flanges and extending over the full length of said opening; and a detachable flexible padded flap adapted to close said opening after the receptacle has been removed; the arrangement being such that the removal and closing of the flap, and the insertion and removal of the receptacle can all be accomplished by the chair occupant without leaving the chair.