The precipitation of calcium phosphates in the presence of increasing cadmium amount was studied at 25°C in dilute ammoniacal solutions ([Ca] = [P] = 0.005 M). An amorphous precipitate, an apatite-like calcium phosphate and the compound Cd 5 H 2 (PO 4 ) 4 ⋅4H 2 O are found according to pH and Cd concentration. The nucleation of hydroxyapatite is greatly delayed by cadmium, which influences also its crystallinity, but the effect tends to vanish with time. The role of cadmium is discussed.