Abstract: A hidden connector system (10) for railing constructions including a basic railing unit (11) including an elongated hollow tubular railing member (20), the interior surface of which is provided with a generally C-shaped central core element (21) that is supported within the interior of the railing member (20) by a pair of opposed struts (22) (22) wherein, the exterior surface of the railing member (20) may be provided with opposed elongated channels (23) and/or opposed cylindrical recesses (25) that are offset by 90° from the opposed struts (22) (22) and wherein a plurality of railing members (20) (20′) etc. may be connected to one another by conventional fasteners (50) alone or in combination with diverse connector members (60) (70) and (80).