Abstract: A pass-line adjusting mechanism is disclosed in association with the chocks of the lower back-up roll of a four-high rolling mill. The adjusting mechanism includes an axially slidable adjusting member having vertically stepped surface portions corresponding to each lower back-up roll chock, and an inverted channel-shaped support member interposed between the chocks and adjusting member. The support member has hardened upper surfaces underlying the chocks and engaging rocker plates thereon, and cross members providing lower surfaces engaging corresponding ones of the steps on the adjusting member. The support member is adapted to be elevated to lift the lower surfaces thereof from the adjusting member, and the adjusting member is adapted to be displaced relative to the support member when the latter is elevated to selectively position any corresponding pair of the steps thereof beneath the lower surfaces of the support member.