A thrust bearing (16) for transmitting axial thrust forces between at least two gear parts (1, 5) rotating relative to each other in a gear arrangement is provided, with two coaxial, opposing race disks (17, 18) holding a cage (6) with a plurality of roller bodies (7) with radial play. To prevent discharge of lubricant to the greatest possible extent radially from the thrust bearing (16) and accordingly to be able to guarantee a sufficient axial supply of lubricant to the gear arrangement, it is provided that one race disk (17) has a smaller outer diameter than the other race disk (18), that both race disks (17, 18) each have external collars (19, 20) on the radially outer edge that extend axially inwardly, and the external collar (19) of the race disk (17) with the smaller outer diameter is covered axially by the external collar (20) of the race disk (18) with the greater outer diameter, such that an extensive encapsulation of the thrust bearing (16) against lubricant passage is guaranteed.