Objective:To investigate the biocompatibility of nanohydroxyapatite/polyamino acid composite.Methods:In vivo and vitro experiment were estimated for the biocompatibility of nanohydroxyapatite/polyamino acid as follows.①cytotoxinic test

bone marrow mesenchymal stem cell(BMMSCs) were incubated with the composite

the morphology of the cells was observed by inverted phase contrast microscope

CCK-8 were tested to analyze the proliferation of cell.②acute toxic test was divided into 2 groups(n=10) including 20 KM mice weighted 20～23 g

the extracts and physiological saline were injected to mice with 50 g/kg

the toxicity manifestation were observed.③hemolytic test consist 3 groups

0.2 ml anticoagulant diluted fresh rabbit blood was added to 10 ml extracts

sterile distilled water and physiological saline each

the percentage of hemolysis was examined.④pyrogen test

3 rabbits weighted 2.3～2.5 kg were injected in vain with 10 ml/kg extracts

the difference in temperature between the normal body temperature tested and the ones per hour in the next continues 3 hours.⑤bone marrow micronucleus test

30 KM mice weighted 20～23 g were divided into 3 groups

extracts

cyclophosphamide and physiological saline were injected to mice with 100 mg/kg twice at 24 hours intervals

the numbers of micronucleated polychromatic erythrocytes and polychromatic erythrocytes were observed

the frequency of micronucleus was calculated.Results:nanohydroxyapatite/polyamino acid had good biocompatibility with rabbit BMMSCs

and the composite was of no acute toxicity

no pyrogern

no hemolytic effect and no genotoxicity by mouse bone marrow mircronucleus test.Conclusion:nanohydroxyapatite/polyamino acid has good compatibility

can be used as internal fixation material in orthopedics in future.