Abstract: The present invention relates to a seat recliner adjustment mechanism for a wheelchair having an upper back rest frame pivotally mounted to a lower seat frame. The adjustment mechanism includes an elongate rack member pivotally mounted to the lower seat frame and having a plurality of spaced apart detent engaging means extending along one side thereof. A locking mechanism is mounted on the back rest frame and includes a detent element engageable with a selected one of the detent engaging means of the rack member for maintaining the back rest frame in a selected reclined position. The locking mechanism includes a wedge element normally biased in a locked position to urge the rack member into locking engagement with the detent element. The wedge element is moveable to a released position wherein the rack member is disengaged from the detent element to enable the back rest frame to pivot relative to the lower seat frame.