Abstract: An adjustable open-end wrench having an elongated body member, one end of which is a handle, and the other end of which includes a fixed jaw portion and jaw-base portion having a reentrant groove therein with a movable jaw member slidably mounted in the reentrant groove and a rack portion on the bottom of the movable jaw member for interaction with a second rack member located in another chamber in the body member located just below the reentrant groove, that chamber also housing the interior end of a button member which extends to the exterior edge of the wrench body member, and a lever member and biasing means for biasing the button member outwardly while biasing the rack members into engagement with each other. By simply pushing the exposed portion of the button member, the movable jaw is released for slidable adjustment of the width of the open-end wrench opening.