In this study, the friction and wear behaviour of chilled and borided GG25 gray cast iron, as used in industry, were investigated. Its surface properties, microstructures, hardness distribution and wear behaviour were determined as well as the wear characteristics and weight losses of treated samples as a function of wear test duration and load. The results indicated that the surface of chilled samples has ledeburite with cementite layer and the borided sample has Fe2B and Fe3B borided layers. The surface hardness and wear resistance of borided samples are greater than those of chilled samples. (C) 2000 Published by Elsevier Science S.A.