Abstract: A device for fastening a guide rail (3) to a wall (1), particularly a rear wall of a slide guide, comprises a guide rail (3), on which a bent web-shaped holding device (6) is provided on the end side, which holding device (6) can be connected with a fitting (2) which can be fixed on a wall (1), the fitting (2) having an upper and a lower side wall (20, 21) which are mutually connected on a guiding section (26) by way of a rearward wall (22) and a forward wall (23). The web-shaped holding device (6) is displaceably disposed in the guiding section 26. According to the invention, the fitting (2) has a side wall (24) spaced away from the guiding section (26), and the guide rail (3) can be continuously displaced between a first end position, in which the guide rail (3) rests laterally against the guiding section (26), and a second end position, in which the guide rail (3) rests against the side wall (24). In this case, an unintentional detaching of the guide rail (3) from the fitting (2) is avoided.