It is widely known that particle size reduction processes have a low energetic efficiency. In this paper, we present experimental results obtained by a new grinding machine using ultrasound to enhance the performance of a roller mill. The required energy consumption for a comminution operation appears to be significantly reduced by careful application of an ultrasonic field in the grinding zone. A lower stress on the shafts and a reduction of the required torque were also observed. The lower mechanical stress should also cause less abrasive wear on the rolls. (C) 2003 Elsevier Ltd. All rights reserved.