Abstract: A hydrodynamic retarder having a first blade wheel and having a second blade wheel concentric thereto, together forming a hydrodynamic circuit grouped about a common rotary axis. Each blade wheel is made of a base body and a blade arrangement fixed thereto including a plurality of blades. The hydrodynamic circuit is supplied by a fluid inlet, while the fluid removal from the hydrodynamic circuit is performed by a fluid outlet. The fluid inlet has an inlet spiral enabling tangential fluid flow and the fluid outlet has an outlet spiral enabling tangential fluid flow. At least one inlet spiral is associated with a flow guide guiding the fluid into the hydrodynamic circuit with at least one axial component.