Assembly system for tubular metallic frames (10) for chairs, armchairs and/or benches, the tubular frames (10) being able to be associated with seats, chair backs, arms, flat surfaces or other parts, padded or not, the frame (10) consisting of a plurality of base components (12) of one or more tubular elements (13), the base components (12) having a substantially two-dimensional development, each of the base components (12) integrally including respective male elements (24) or female elements (25) with a speedy pre-assembly coupling cooperating with mating female elements (25) or male elements (24) with a speedy coupling on another of the base components (12), in the pre-assembly condition, the base components (12) including, in an intermediate position on a relative tubular element (13), respective aligned holes (27) for the insertion and clamping of at least a clamping rod or bar (28).