Microcrystalline diamond thin films were deposited on cemented tungsten carbide cutting tools by hot-filament chemical vapour deposition process. The coatings deposited were irradiated with 50 MeV Si7+ ions upto a dose of < 10(13) ions cm(-2). The adhesion and wear characteristics of as-deposited and irradiated coatings were studied and it was found that irradiation induced increased adhesion of the coatings to the substrate resulting in reduced coating failure during wear tests.