An adjustment fitting, in particular for a vehicle seat, includes a first fitting part and a second fitting part that can be rotationally adjusted relative to the first fitting part about an axis of rotation. An external gear, which has internal teeth and into which an internal gear that is associated with the second fitting part and has external teeth is inserted eccentrically to the axis of rotation like an eccentric gear, is associated with the first fitting part. The internal gear forms an eccentric receiving space towards the axis of rotation. The adjustment fitting further comprises an eccentric member that is rotatably inserted into the eccentric receiving space, and a drive shaft for driving the eccentric member. The external gear is designed as a ring gear that has a bottom and an external wall which axially extends beyond the internal teeth and embraces the external teeth of the internal gear by means of a radially inward-oriented collar. In addition, the internal gear comprises an internal wall which axially extends beyond the external teeth and axially penetrates the collar. The fitting parts are thus securely fastened in the axial direction while access is made easy, especially for mounting the adjustment fitting on a vehicle seat or a seat adapter.