The wear of drilling tools in mining and tunnelling has always been a predominant factor for the costs of hard rock excavation. This fact is not only related to material and personnel costs arising from drill bit maintenance and replacement but also because of the direct and negative impact of a worn drill bit on the drilling performance. This paper presents typical machinery, tools and basic findings on wear and performance interactions as well as drilling tool wear mechanisms. Based on this theoretical background, methods and classifications for on-site investigation of encountered tool wear rate and wear types are presented. The paper then summarises laboratory approaches for assessing of rock abrasiveness in order to predict drilling tool wear from geotechnical investigations.