An adjustable gage block for a press brake comprises a base attachable to the press brake and a body pivotally carried by the base for pivoting movement about a vertical axis. The body carries a first guide member, and a second guide member is pivotally carried by the body for pivoting movement about said vertical axis with respect to the first guide member. One or both of the guide members have upwardly-facing guide surfaces laying in a horizontal plane to support a workpiece, and each guide member has a vertical guide surface, with the vertical guide surfaces laying in convergent planes. Adjustment means are provided for adjusting the angle between the vertical guide surfaces of the guide members to accommodate the shape of a workpiece. Desirably, a workpiece support is mounted to the press brake spaced from the gage block, the workpiece support having an edge guide surface positioned to engage an edge of the workpiece and to orient the workpiece with respect to the gage block.