A cyclonic separation device comprises a plurality of cyclonic separators fluidly arranged in parallel with each other, each cyclonic separator comprising a chamber 18 having a circular-section side wall 19, a fluid inlet 20 and a fluid outlet 21 disposed at one end of the cyclone chamber 18, and an opening at the second end of the cyclone chamber 18 through which separated matter passes out of the chamber for collection. The cyclonic separators are arranged in a rotatable body 17 such that their respective cyclone axes B are outwardly inclined relative to an axis A of rotation of the body 17 and such that the second end of each cyclone chamber 18 is disposed radially outwardly of its first end with respect to the axis A of rotation. A motor 15 rotates the body 17 about its axis A of rotation and so imparts a radially outward force on separated matter forced against the side wall 19 by the cyclonic action, the radial force serving to rapidly force the matter axially of the towards the opening. The separation efficiency is thereby improved by the radial force.