An irrigation sprinkler and sprinkler nozzle assembly including a self contained pressure regulator and flow control ring, which can be assembled with a desired spray deflector, shrub bubbler or rotating stream distributor on the top of the nozzle assembly. The pressure regulator housing is incorporated into the center of the nozzle assembly and includes a reference pressure chamber connected to atmospheric pressure with a spring bias enclosed to bias a pressure responsive movable member that is connected to an upstream pressure balanced flow throttling valve. A combination deflector pop-up pressure regulating mechanism housed in the filter of the nozzle housing assembly is also shown.