A flow rate regulator (1) having a regulator housing (2), wherein said regulator housing (2) has an outer circumferential edge region (5) that can be placed on an end circumferential edge region (3) of a jet regulator (6) and/or of a sieve (11) and including a central annular gap (12), in which an annular throttle body (13) made of elastic material is present, bounding a control gap (15) between same and an inner and/or outer circumferential wall (14) of the annular gap (12) having a control profile, wherein the open flow-through cross-section of said control gap is changeable under the pressure of the flowing water. The flow rate regulator (1) according to the invention is characterized in that said regulator has a shell-shaped regulator housing (2), the outer circumferential edge region (5) of which is designed as a radially outwardly protruding ring flange, and in that the inner shell chamber (18) of the regulator housing (2) open to the outlet side is dimensioned for receiving a sub-region of the sieve (11) protruding past the end circumferential edge region (3) of the jet regulator (6).