Abstract: Sliding bolt door locking apparatus that may be installed on the inside or outside surface of any door, and which may be installed on any side of the door. The sliding bolt locking apparatus may be easily bolted to an existing door and does not require removal of significant material for installation. The apparatus may be installed on the interior surface of a hinged door, and on any side of the door, including that side of the door having the hinge. Four separate sliding door locking apparatus assembles may be installed on the four interior sides of a hinged door for increased security against unwanted entry.