A technique which allows dietary analysis to be extended to samples older than 10,000 years by ₁₃C analysis of inorganic bone constituents is presented. The bone carbonate phase is removed leaving bone hydroxyapatite and collagen. The hydroxyapatite is treated with dilute hydrochloric acid under vacuum to give carbon dioxide; the remaining insoluble collagen is then refined to pure bone gelatin. The bone gelatin is combusted to release carbon dioxide. The hydroxyapatite of bone contains about 8% more ₁₃C than bone gelatin. Bone apatite derived from a pure C₃ diet has a delta₁₃C of around-13. 5% whereas that derived from a C₄ diet has a value of approximately + 1%. The values for gelatin are about -21.5 and about -6.5% respectively. The delta ₁₃C of gelatin and hydroxyapatite relative to the food web is approximately +5(C ₃) and 6%C₄) for the gelatin and about 13% for the hydroxyapatite. -- AATA