Hydroxy carbonated apatite (HCA) powders were prepared by precipitation from a modified SBF solution (5x M-SBF). The ionic concentrations were 5 times higher than in human blood plasma with the exception of Mg2+ and HCO3 - concentrations that were reduced in order to accelerate crystal growth. Spheroaggregates of HCA platelets with molar (Ca+Mg)/P ratios ranging from 1.44 to 1.56 were obtained after precipitation at 50 °C. The crystallite size in c-direction was approximately 20 nm and depending on the precipitation time a CO3 2- content of 1.8 to 5.2 wt.-% was determined. Using this low temperature precipitation method, HCA powders with a high specific surface area of 83 m2/g and a composition and crystallite size close to those of the mineral phase of human bone were obtained.