The lower ends of two vertical standards are received in sockets provided on the sideboards of a pick-up truck box, the upper ends of the standards being connected by a detachable bridging member. A boom assembly is pivotally mounted on one of the vertical standards, and is swingable from a position outside the truck box to a position disposed over the box, the boom assembly carrying a winch and cable assembly for lifting heavy objects. When not in use the boom assembly is movable into alignment with the bridging member for storage, where it is secured. In one embodiment the boom assembly is extendable, to enable handling elongated objects. The hoist is designed for easy mounting on and removal from the truck box.