Abstract: An anti-backlash nut assembly is disclosed for longitudinal movement along a screw which has an external thread thereon, in response to relative rotational movement between the nut assembly and the screw. The assembly includes a first nut part having an internal thread complementary to the external thread of the screw, and a second nut part also having an internal thread complementary to the external thread of the screw. A coil spring is interconnected between the first and second nut parts for applying torque thereto and rotatably biasing the nut parts together to eliminate backlash therebetween and improve the positional accuracy of the nut assembly along the screw. A cylindrical collar is sandwiched between a pair of opposed portions of the nut parts and surrounds the coil spring. With this structural combination, the anti-backlash nut assembly can be adjustably preloaded by relatively rotating the nut parts to selectively preload the coil spring to a desired torque.