Abstract: This chair structure is convertible from a wheelchair seating mode to a horizontal or prone mode and includes a base having ground wheels attached thereto and providing a mounting for a chair superstructure. In the seating mode the superstructure includes back and front portions interconnected by seat and arm portions which cooperate to form a folding linkage system. The back portion is rotatably mounted to a post forming part of the base, and the seat portion is adjustably mounted to the base, so that when the back portion is rotated about the base post, the back, front, seat and arms are unfolded into a substantially unobstructed horizontal platform in the prone mode. The substantially flat, horizontal platform can be moved into overlapping relation with a hospital bed to permit a patient to be easily transferred onto the platform which is then folded into the seating mode for transportation of the patient to a different hospital station.