The invention relates to a stirring device for activated sludges comprising a hyperboloid stirring body (2) attached to a shaft (1), wherein a plurality of transport ribs (3) are provided on the top (O) of the stirring body (2) running toward the circumferential boundary (UM) thereof, wherein the transport ribs (3) have an oblique course, at least in sections, relative to a radial direction, and wherein an oblique position of the transport ribs (3) is selected such that, when the stirring body (2) rotates in a predetermined rotational direction (R), a flow is generated that is directed radially outward away from the circumferential boundary (UM) of the stirring body (2). In order to improve the efficiency of the stirring device, the invention proposes that at least one propeller (6) be attached to the shaft (1) that, when the stirring body (2) rotates in the rotational direction (R), generates a flow (A) directed toward the top (O) of the stirring body (2).