The invention proposes a subassembly of a hydraulic variable valve train of an internal combustion engine, having a guide bushing (4) that can be installed in a hydraulic housing (3), and having a piston (5) supported therein so as to be axially movable for actuating a gas exchange valve (1), and having a valve element (7) that, together with the end face (10) of the piston distant from the gas exchange valve, defines a hydraulic pressure chamber (11) in the guide bushing, wherein the valve element is a throttle check valve that allows hydraulic medium to flow out of the pressure chamber throttled by a continuously open throttle opening (16) and allows hydraulic medium to flow into the pressure chamber with little throttling by a ball check valve (17). The subassembly is intended to be implemented as a modular unit assembled outside of the hydraulic housing, wherein the guide bushing and the valve element are fastened to one another, and the piston is secured in a captive manner in the guide bushing.