A longitudinal adjuster for a vehicle seat may have at least one seat rail pair, which is formed from a lower seat rail and an upper seat rail, which is guided for sliding in the longitudinal direction relative to the lower seat rail. The two seat rails of the seat rail pair may engage around one another. The lower seat rail or the upper seat rail may have at least one opening. The at least one opening may have an opening cross-section, the two upper corner regions of which each have a curvature portion may have a radius which continuously changes of the course of the curvature portion. A vehicle seat with the adjuster is described.