Laboratory testing of uranium ores is an essential step in the economic evaluation of uranium occurrences and in the development of a project for the production of uranium concentrates. Although these tests represent only a small proportion of the total cost of a project, their proper planning, execution and interpretation are of crucial importance. This manual discusses the objectives of metallurgical laboratory ore testing, shows the specific role of these tests in the development of a project and provides practical instructions for performing the tests and for interpreting their results. Guidelines on the design of a metallurgical laboratory, on the equipment required to perform the tests and on laboratory safety are also given. Contents: 1. Introduction; 2. Sampling and characterization; 3. Size reduction; 4. Leaching; 5. Solid–liquid separation and washing; 6. Uranium recovery from leach solutions; 7. Uranium recovery by ion exchange; 8. Uranium recovery by solvent extraction; 9. Precipitation; 10. Alternative techniques; 11. Flow sheets and material balances; 12. Report writing; Appendix I: Laboratory safety; Appendix II: Guidelines for laboratory design; Appendix III: Suggested laboratory equipment and supplies.