Disclosed is an orthopedic and dental implant ceramic composition comprising hydroxyapatite and whitlockite. Said composition is prepared by blending 50 to 99.5% by weight of a crystalline hydroxyapatite and 0.5 to 50% by weight of whitlockite, and then, sintering the blend at a temperature of 900.degree. to 1,400.degree. C. Said crystalline hydroxyapatite is prepared by the solid phase reaction wherein a mixture of a calcium phosphate, having a Ca/P ratio of 1.5 to 1.67 by mole, and a stoichiometric amount or more of a calcium compound is heated at a temperature of 500.degree. to 1,000.degree. C. Said calcium compound is at least one compound selected from the group consisting of CaCO.sub.3, CaO, Ca(OH).sub.2, CaF.sub.2, Ca(COO).sub.2, Ca(NO.sub.3).sub.2 and CaCl.sub.2.