Abstract: Objective To investigate the acute toxicity of Deinococcus radiodurans ( DR) and its broken products. Method The KM mice were administrated with 0. 4 mL / 10 g of 1×10⁹ / mL DR ( high concentration DR group) , 1×10⁷ / mL DR ( low concentration DR group) , 1 × 10⁹ / mL DR broken products ( high concentration DR debris group) , 1×10⁷ / mL DR broken products ( low concentration DR debris group) and Tryptone Glucose Yeast agar medium ( TGY medium group) , respectively. After intragastrically administrated twice a day every 8 hours, the mice were observed for 14 days, then the organ coefficient, body weight, blood routine ( white blood cell, lymphocyte, red blood cell, hemoglobin, hematocrit, mean corpuscular volume, platelet) and plasma biochemical indexes ( alanine aminotransferase, aspartate aminotransferase, total protein, creatinine, creatine kinase, magnesium, phosphorus, creatine kinase MB isoenzyme, lactate dehydrogenase) were used to analyze and evaluate the toxicity of DR. Result No abnormal secretion, defecation, respiration and movement were found in mice in different dose groups. From 0. 5 hour after administration to the end of the experiment, no abnormalities such as slow reaction, pupil change, eyeball protrusion, eyelid ptosis and skin color change were observed in the test mice.There were no significant differences in body weight, blood routine test and blood biochemical indexes in the trialgroups compared with TGY group. The spleen coefficient was significantly increased in the low-dose group, and the spleen pathological examination showed that there was no substantial lesion. Conclusion The live and broken DR have no acute toxicity to mice. This experiment provides experimental basis for clinical application of DR.