Rotating cones were used to carry out fibre fractionation of a 100% hardwood pulp having a consistency of 0.93 +/- 0.02%. The unique features of the rotating cone fractionator adopted in this study were that its surface was constructed from a sieve mesh, thereby introducing a "rough" surface, and the feed pipe was located at an off-centre position to the axis of rotation. In all earlier studies reported in the literature, the fibre fractions were collected at different radial locations. However, in the present study, collection of the various fractions was made either at different radial or at angular positions. Tests were conducted for 120 mm diameter cones having a cone angle of 30 degrees. Visual observations, photographs and fibre length measurements suggested that fibre fractionation performance strongly depended on the flow characteristics formed on and surrounding the rotating cone. In turn, they were found to be strongly dependent on the surface roughness, rotational speed and feed flow rate. Results for fibre fractionation showed quite conclusively that rotating cones made from 20-mesh and 32-mesh screens were more effective for fibre fractionation than "smooth" surface rotating cones.