A disc brake, in particular for commercial vehicles, has an adjustment device for compensating for brake lining/brake disc wear. The adjustment device is arranged at least partially inside an interior space of the brake caliper and has an adjustment gear with an adjustment nut having an internal thread, and an adjustment spindle screwed therein with an external thread. For adjustment during normal operation of the brake, the adjustment nut is rotated in relation to the adjustment spindle, which is fixed against rotation. A first sealing device at least partially seals off an annular space on the brake disc side between the inner wall of a through-opening in the brake caliper and the axially adjustable adjustment spindle, which extends through the through-opening and toward one of the brake linings, wherein the first sealing device is held on the caliper at one end.