Porous hydroxyapatite ceramics could be obtained using as raw materials seaweed, corals and animal bones. Three dimensional structure of human bone and peculiarities of crystalline structure are the main factors that persecute the development of artificial bone substitutes. The concept of functionally graded structures [1] seems to be more prospective developing tailored reactions with an environment as also optimizing implant material response to mechanical loads. The present work is devoted to the influence of hydroxyapatite (HAp) particle size and subsequent heat treatment of dry pressed Hap powders green bodies onto hydroxyapatite ceramic sintering and resultant ceramics structure and properties. Sol-gel derived matrix for preparation of HAp dispersions was used to develop thermal treatment induced porosity.