Abstract: A modular shelving system assembly is constructed from a combination of tubular frame elements of a rectangular shape provided with a series of spaced aligned openings in opposed inner faces of both of the long side rails and the inner and outer faces of both of the short side rails are provided with a plurality of spaced aligned openings. The two side faces of at least one of the long side rails include aligned openings laterally spaced similarly to the openings in the short side rails. A plurality of identical frame elements may be connected to one another by means of appropriate fasteners fitted in related aligned openings with a short side rail connected to another short side rail to form a vertical column of frame elements. The opposite short side rails of additional similar frame elements are connected to adjacent long side rails of similarly constructed vertical columns to provide horizontal brace members and provide an integrated shelving unit.