Abstract: A perpendicular connection of two profile rods abutting at an angle (&agr;) with undercut linear grooves has a connecting bolt with a head at one end. This is arranged parallel to the axis of symmetry of a longitudinal profile rod in an undercut linear groove therein, and engages with its other end in a tenon block arranged in an undercut linear groove of the transverse profile rod. A spread element inserted in the undercut linear groove can be spread by the effect of an axial force generated by the connecting bolt transverse to the linear groove and firmly clamped in this as an abutment. The spread element comprises a spread body with an axial holder bore and a wedge body which can be inserted therein with the through bore for the connecting bolt, where the head of the connecting bolt lies against a face of the wedge body.