Abstract: A rotating stream nozzle is provided particularly for use as an irrigation sprinkler, wherein the nozzle provides a plurality of outwardly directed and discrete water streams which are rotated in steps through a prescribed arcuate spray path. The rotating stream nozzle is adapted for mounting onto a water supply conduit and includes a swirl plate through which water under pressure flows with a swirling action into a relatively small drive chamber. The swirling water flow forces a drive ball within the drive chamber to move into repetitious impact engagement with raised anvils formed on the inner diameter surface of a cylindrical rotor lining the drive chamber and mounted for rotation within a nozzle cap. The rotor is displaced through a small rotational step each time the drive ball strikes one of the anvils, and the water is discharged from the nozzle as discrete rotating streams passing through small discharge ports in the rotor.