Abstract: A self-locking mounting bolt system for use in mounting shelf boards to side walls of a type employed in furniture. The mounting bolt system includes a plurality of bolts fixedly attached to the side walls, each bolt having a frusto-conical head. The shelf board has formed in each end portion thereof complementary recesses adapted to receive the bolts therein. A larger diameter portion of the bolt head is disposed further away from the side wall than a small diameter portion of the head so that dovetailing of the bolt head and the recess provides the ridigized right angle interconnection of the shelf board and the side walls. Another plate member of equal width to the shelf board may be placed coextensively thereon to clamp the head of the bolts therebetween by means of fasteners.