Abstract: A machine vise having a first jaw with a flat, inwardly disposed inner face, a second jaw with a flat, inwardly disposed inner face opposing the inner face of the first jaw, a jaw plate carried by each jaw and including a block-like body with a flat face in bearing engagement with the inner face of the jaw and a flat, inwardly disposed work-engaging surface, fastener means securing the body on the jaw, one or both of said jaws includes a vertically adjustable steady rest comprising an elongate work-engaging bar adjacent to and extending laterally of said work-engaging surface, an elongate vertical guideway in the body and opening at the work-engaging surface, a guide block fixed to the bar and slidably engaged in said guideway and an elongate vertical jack screw carried by the body for free rotation and against axial movement and extending longitudinally through said guideway and threadedly engaged through said block.