System for manufacturing frameless windows which comprise a transparent pane, the lower edge of which is fixed in the slot of one or more holders by at least one layer of adhesive, which system comprises a work-table suitable for supporting the pane with the lower edge turned upwards and one or more mobile supports suitable for moving downwards the holders toward the pane, so that the holders can be inserted astride the lower edge, turned upwards, of the pane. In addition, a process is disclosed which can be carried out with the system.