A longitudinal adjuster (10) for a vehicle seat (1) includes at least one rail pair (12) with a longitudinal direction (x) relatively sliding and engaging first seat rail (14), for connecting to a seat frame side part (6), and a second seat rail (16), for connecting to a vehicle structure. A first clamping element (20), fastened to the first seat rail and a second clamping element (22), fastened to the second seat rail are usually spaced apart from each other and engage with each other, in response to a defined application of force, for example in the event of a crash. The first clamping element has a connection section (24), which can be connected to a surface (8) of a seat frame side part (6) directed toward the rear. The vehicle seat includes the longitudinal adjuster and a seat frame side part, which is connected to a first seat rail.