A hydraulic valve lash adjuster with idle stroke function for a valve train of an internal combustion engine, said hydraulic valve lash adjuster comprising a piston (2, 2′, 2″) that is guided for displacement in a piston housing (4) and elastically supported against said housing (4), said piston (2, 2′, 2″) comprising a low pressure chamber (3) that communicates via an axial opening (7) in a piston bottom (8) with a high pressure chamber (5) defined by the piston housing (4) and the piston (2, 2′, 2″), and further comprising a control valve (9, 9′, 9″, 9′″) acting between said pressure chambers (3, 5), said control valve (9, 9′, 9″, 9′″) comprising a valve closing body (10, 10′, 10″) that can be brought to bear sealingly against a valve seat (15, 15′) that surrounds the axial opening (7) on a piston body undersurface (18) and is received in an element (12, 12′) that limits a closing body stroke (17), and said control valve (9, 9′, 9″, 9′″) further comprising a control valve spring (11) that loads the valve closing body (10, 10′, 10″) with a spring force in opening direction, and an idle stroke being produced during a collapsing movement between the piston (2, 2′, 2″) and the piston housing (4) during which said valve closing body (10, 10′, 10″) is hydraulically loaded in closing direction against the action of the control valve spring (11) by a pressure build-up in the high pressure chamber (5), whereby a retarded pressure build-up can be obtained through a flow control device (23, 23′) arranged on a high pressure chamber-side and comprising a flow control element (24, 24′) and a medium pressure chamber (19) that extends between the flow control element (24, 24′) and the axial opening (7) of the piston (2).