Abstract: An open-end self-adjusting ratchet wrench comprising a generally C-shaped head portion defining a holding space sized for receiving a fastener therein, a ratcheting surface formed on the head portion and facing the holding space, and a plurality of circumferentially spaced notches formed on the ratcheting surface in communication with the holding space; a handle coupled to the head portion; and a spring-loaded tooth mechanism extendably seated within the notches of the head portion for applying a grip to a fastener disposed within the holding space of the head portion when the handle is torqued in one direction and for releasing the grip of the fastener when the handle is torqued in an opposite direction.