The distribution of cadmium between calcium phosphate and solution has been investigated, when calcium phosphate is precipitated from calcium nitrate, diammonium hydrogen phosphate and cadmium nitrate solutions containing sodium chloride (0, 0.53 mol/1) or magnesium chloride (0, 5.0 X 10-2mo1/1) at 25 and 100°C: Cadmium in the parent solution is mostly incorporated in hydroxyapatite as a solid solution between hydroxyapatite and apatitic cadmium phosphate.