This study was performed to evaluate the actue sbucutaneous toxicity of hydroxyapatite sinter produced from tuna bone in Sprague-Dawley(SD) rats. Hydroxyapatite sinter was administrated at dose levels of 5000, 2500, 1250, 625, 312.5 and 0 mg/kg. After single subcutaneous adiminstration to both sexes to both sexes SD rats, we observed rats for 14 days. Hydroxyapatite sinter did not induce any toxic signs inmortalities, clinical findings, body weights and gross findings of the rats. In view of result, it was impossible to estimate LD/ sub 50/ values in SD rats. In conclusion, these results suggest that hydroxyapatite sinter produced from tuna bone has no effect on acute subcutaneous toxicity in SD rats.