The present invention pertains to a longitudinal adjustment device for vehicle seats, in which the seat is attached along each of its long sides to runner rails 10, mounted with freedom to slide in guide rails 15, which are attached to the vehicle. Each runner rail 10 has a locking device, which can be released from its connection to the guide rail 15. The locking device comprises a release lever 21, 22, supported with freedom to swivel on each runner rail 10, to move the device into its released position, which lever is to be shifted via rods 31, 32 of an actuating element 30 supported on the runner rails 10. The adjusting moment exerted on the actuating element 30 is transmitted to the rods 31, 32 via a differential, where the rods 31, 32 are disconnected from each other. As a result, each rod can be moved until the locking device has been moved completely into the position in which it is released.