The present manual is part of the lAEA’s programme on guides on uranium resource assessment and supply. Its purpose is to describe methods of making numerical estimates of undiscovered uranium endowment and of the economic potential of the uranium resources. It provides guidance on choosing the method(s) most applicable to a given situation. Contents: 1. Introduction; 2. Geological analogy principles; 3. Control areas; 4. Approaches to estimation of endowment; 5. Probability considerations; 6. Limited information and subjective probability; 7. Deposit density methods; 8. Mineralized rock density methods; 9. Crustal abundance methods; 10. Economic potential evaluation; 11. Criteria for method selection; 12.Utilization of resource estimates; Appendix I: Glossary; Appendix II: Selected control area descriptions and gradetonnage curves; Appendix III: Case studies.