A seat underframe for motor vehicle seats, with two pairs of rails arranged at a distance from each other and each having a seat rail and a floor rail, a seat carrier, in each case two pivoting arms which are connected at one end in an articulated manner to the seat carrier and at the other end in an articulated manner to the seat rails and fix the maximum distance between the seat carrier and the seat rails, and a drive unit adjusting the seat carrier between a lower starting position and an end position. The drive unit for adjusting the seat carrier is formed beyond a height end position which is fixed during normal operation.