The ready availability and the low cost of oyster shells, which is composed predominantly of calcium carbonate with rare impurities, along with natural wastes are attractive features for converting the biological material into hydroxyapatite (HA) powders for biomedical applications. The HA powder was synthesized using oyster shell powders and dicalcium phosphate dihydrate (CaHPO4.2H(2)O, DCPD) through ball milling and subsequently heat treatment. The HA was initiated through sintering the 1-h milled sample at 1000 degrees C for 1 h, while pure HA phase is formed after sintering the 10-h milled sample. The as-prepared samples, obtained after 5 or 10 h of milling and then heat-treating at 1000 degrees C for 1 h, contain the phase of beta-tricalcium phosphate (beta-TCP). Moreover, the result of FTIR analysis showed that the as-prepared HA sample is A- and B-type carbonate-containing calcium phosphates. The assynthesize HA powder containing trace elements Mg and Sr exhibited good crystallinity (96.3%) and high phase-purity. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.