A rock bolt comprising an elongated bar and an elongated deformable member, with a threaded nut to reduce the distance between the respective ends of the deformable member so as to deform at least part of the member away from the bar. The threaded nut may be located at the distal end of the rock bolt or the proximal end thereof. Though the term "rack bolt" is used, the bolt may be used as a ground anchor, or in other suitable applications, in which it is located in a hole drilled into earth as well as or instead of rock.