A dirt separator for a vacuum cleaner including a chamber having an inlet through which dirt-laden fluid enters the chamber and an outlet through which cleansed fluid exits the chamber; and a disc located at the outlet, the disc being arranged to rotate in a predetermined direction about a rotational axis, and including holes running from an upstream face to a downstream face through which the cleansed fluid passes. When viewed along the radial direction of the disc, the path of each hole through the thickness of the disc defines a centreline, the centreline being inclined such that it is non-perpendicular to the disc. The centreline of each hole is inclined such that it intersects the upstream face of the disc at a point which is behind, in the direction of rotation of the disc, the point at which the centreline intersects the downstream face of the disc.