Long-term leaching tests on full-size radioactive blocks have been undertaken since 1979 in the leaching facility of the Nuclear Research Center of Saclay. The aims of the tests are the assessment of the release of radionuclides into the biosphere, measurements of ion transfer between the blocks and the environment, and understanding of the transfer mechanisms. After a general presentation of the blocks submitted at the tests, and a description of the leaching facility, examples of results are given; they concern the balances of activities released, post-leaching appraisal, and investigations of mechanisms of leaching experiments.