Abstract: Apparatus for use in the bleeding of fluid systems, especially the hydraulic brake system of a motor vehicle, comprises fluid pumping equipment (1) for pumping fluid to a main fluid reservoir (8) of the fluid system via a supply conduit (24). The pumping equipment (1) includes a fluid container (6) and an air pump (2) serving to discharge fluid from the container (6) into the supply conduit (24). The pump (2) is driven through an electric circuit (C1.C2) including a fluid pressure control (14) and a fluid level control (15A) of the container (6). The delivery end of the supply conduit (24) passes through an opening (26) of the reservoir (8) which opening (26) is sealed by an elastomeric plug (18) laterally expandable by a compression device. The above apparatus considerably conveniences the bleeding of motor vehicle brake systems.