Hydroxyapatite powders prepared by wet method from Ca(OH)2 and H3PO4 and calcined at 800°C were sintered in air at a temperature from 1100° to 1400°C for 2h. The obtained ceramics with relative densities of 73±2% (1100°C) -89±2% (1400°C) were HIP'ed under 100 or 500MPa of Ar at 900° or 1100°C for 2h without any capsules. The post-sintering at 1100°C under 500MPa brought about densification up to 97% for the samples more than 90% dense having closed pores, but it barely increased the density of samples with lower densities. Transparent apatite ceramics were obtained by HIP'ing.