A surface treating appliance includes a first cyclonic separating unit including at least one first cyclone, a second cyclonic separating unit located downstream from the first cyclonic separating unit and including at least one second cyclone, and a third cyclonic separating unit located downstream from the second cyclonic separating unit and including a plurality of third cyclones arranged in parallel about an axis. Each third cyclone has a fluid inlet and a fluid outlet. The plurality of third cyclones are divided into at least a first set of third cyclones and a second set of third cyclones, with the fluid inlets of the first set of third cyclones being arranged in a first group and the fluid inlets of the second set of third cyclones being arranged in a second group spaced along said axis from the first group.