This is an overview of all the important issues involved in selecting suitable sites, design and construction methods for preparing repositories for hazardous waste in crystalline rock. Most of the examples used refer to radioactive waste - this is a reflection of the experience of the author in this field as well as his belief that the same techniques could be used for isolation of radioactive and other hazardous waste. The focus is on the preparation and performance of multibarrier sytems of rock, waste containers and sealing components in a long-term perspective. Examples are provided from large-scale field experiments conducted in the international Stripa Project (a project to develop and test techniques for isolating highly radioactive waste). This monograph should be of particular interest to environmental geologists, structural geologists and civil engineers.