Abstract: A locking grate for a floor sink includes a screen member having holes dimensioned to allow the passage of liquid but prevent the passage of solid waste and a mounting hole, a threaded member dimensioned to extend through the mounting hole, and a locking member which is adapted to be engaged by the threaded member. According to a presently preferred embodiment, the threaded member is a screw having a non-standard or atypical head which requires a non-standard or unusual screw driver. The locking member includes a tube which is orthogonally engaged by the screw and which has at least one rod slideably disposed therein. The tube and the rod are arranged such that when the screw engages the tube, the screw forces the rod to slide partially out of the tube. The end of the rod which extends out of the tube is preferably provided with a surface which frictionally engages the inner wall of the floor sink drain pipe.