Abstract: Objective To evaluate acute toxic effects of nanosilver via tail intravenous injection in mice.Methods The nanosilver was dispersed by saline at the dose of 12 mg/ml(high-dose group, HG), 3 mg/ml(moderate-dose group, MG), and 0.75 mg/ml(low-dose group, LG).The mice were treated with nano silver suspension via a single tail intravenous injection at 10 ml/kg and the control group(CG) were treated with saline.The mice were sacrificed at 7th or 14 th day after the treatment and the blood was collected for biochemical analysis.The samples of main organs were collected for histopa thology analysis and viscera indexes detection.Results After a single intravenous in jection with nanosilver suspension, the levels of total prote in (TP) (50.17±4.71 g/L) and album in(ALB) (13.83±1.47 g/L) in LG were significantly decreased compared with those of the CG (P<0.05).The levels of TP (48.67±3.61 g/L) and ALB (13.33±1.03 g/L) in MG were significantly decreased compared with those of the CG (P<0.05).The level of lactate dehydrog enase (LDH) (789.00±341.03 IU/L) was significantly increased in LG compared with that of the CG (P<0.05) at the 7 th day.The level of glutamate oxalate transaminase(GOT) (100.00±17.19 IU/L) was decreased in LG compared with that of the CG, and the levels of LDH (667.00±217.24 IU/L) and blood urea nitrogen(BUN) (8.93±1.03 mmol/L) were increased in MG compared with those of the CG at the 14th day (P<0.05).The inflammatory cell infiltration in the alveolus and diffuse edem a and cytoplasmic relaxation in the liver were observed in the HG.Conclusion Tail in travenous in jection of nanosilver at experiment dose could lead to damages in lung, liver and kidney in mice.