Abstract: A self-locking grate for a drain fitting body includes a plate having strainer holes and arcuate elongated openings near the periphery of the grate. Enlarged diameter portions of the elongated openings fit over studs connected to a drain, and the grate can be rotated to engage the studs, so that the grate is wedged to the drain fitting body without the use of screws. An inclined ledge, formed in the elongated openings, acts as a cam surface to wedge against the grate as it is rotated into the locked position. Despite the absence of screws, the grate is unlikely to loosen due to vibration or shock. A tool capable of simultaneously engaging distinct holes in the grate can be used to rotate the grate between the locked and unlocked positions. The invention also includes a kit for converting a conventional drain fitting and grate into a drain fitting and grate of the present invention.