Calcium and phosphor compounds have been used as biomaterials in the medical and odontological field to replace bone tissue. Calcium pyrophosphate (Ca2P2O7), synthetic hydroxyapatite [Ca-10(PO4)(6)(OH)(2)] and natural hydroxyapatite from bovine bone were obtained by powder process, milled and characterized by chemical and crystallographic techniques. The toxic effect of these compounds on cells was evaluated by a cytotoxicity test, a quantitative method of colony suppression assay using Chinese Hamster Ovary (CHO) cultured cells in contact with diluted extracts of the bioceramics. The results showed that only natural hydroxyapatite from bovine bone presented cytotoxic effect in the in vitro test of biocompatibility.