A major difficulty associated with growing diamond on cemented carbide is the cobalt binder that can cause graphitisation of the growing diamond film. This study investigates the influence of two pre-treatment methods, acid leaching and silicide formation, on the erosive impact resistance of the diamond films. The diamond films were deposited onto the treated cemented carbide substrates (6% Co) using a microwave Surfajet technique. The erosive performance was investigated using a centripetal erosion tester in which SiC particles (60-180 mesh size) were impacted normally onto the coated substrates at an impact velocity of 12-60 ms(-1). The erosive impact resistance of diamond was found to increase with him thickness in the range 1-11 mum. The erosive wear performance of the diamond films deposited on the silicide treated carbide were found to be comparable with the performance of those obtained using the acid leaching pre-treatment.