The results are reported of clinical experiments conducted on four volunteers suffering from fractures of the tibia. Dense hydroxylapatite screws were used in association with conventional internal fixation. On removal of the plates and screws at periods varying from 4 to 12 months after implantation, the hydroxylapatite screws were removed together with a core of surrounding bone in order to study the bone hydroxylapatite relationship. Conventional and scanning electron microscopy was used, as well as dichromatic bone mineralometric tests. The results confirmed the excellent biocompatibility of hydroxylapatite with human bone. Arising out of this, the possible future clinical application of dense hydroxylapatite is discussed.