Abstract: A self-propelled wheelchair (1, 101) comprising a frame (2, 102) supporting a seat (3, 103), two drive wheels (5, 105) mounted to the front of the frame, a prime mover mounted to the frame so as to drive the two drive wheels. The wheelchair having at least one castor wheel (7, 107) mounted to the rear of the frame and pivotal about a substantially vertical axis (Y), the frame being height adjustable in such a manner that when the frame is lowered, the seat is simultaneously tilted backwardly. The frame is provided with an anchoring mechanism (116) which allows the wheelchair to be releasably anchored to an anchoring element (119) secured to the floor.