System for the fixing by mechanical seal of glass slabs or the like, particularly usable in the making of panelings of continuous fa?ades according to which, on a tongue (22) obtained on the external part (21) of a first section (2) it is applied a second section (3) constituted by a longitudinal flat strip (31) a lateral edge of which generates an external lip (32) engaging itself on the chamfered edge (B) of the slab (1) of a paneling (P1-P2) from the other edge resulting instead departing at right angles an internal lip (33) able to engage itself on the tongue (22) on which it is fixed by screws (4) fixing so said second section (3) and the slab (1). The tongue (22) will result slanting in a way so that the end of the shank (5) of a screwdriver inserted in the space resulting between two paneling (P1-P2) impacts itself at right angles on the heads of the screws (4) permitting so to replace one or more slabs (1) directly on the entirely assembled fa?ade.