[en] The International Stripa Project was a a cooperative research and development project among several member countries of the Nuclear Energy Agency of the Organization for Economic Cooperation and Development. The scientific and technical objectives of the project were to investigate several aspects of technology concerned with the feasibility and safety of disposal of long-lived, heat-generating radioactive waste at depth in granitic rocks. In particular, the Stripa Project addressed: 1) the development of instruments and procedures to characterize candidate repository sites; 2) the understanding and modelling of groundwater flow and solute transport in fractured crystalline rock; and 3) the design of engineered barriers capable of contributing to waste isolation by restricting groundwater flow in proximity to the waste containers and in the surrounding host rock. This overview summarizes the work focussed on natural barriers and engineered barriers. (author)