AIM To study the effects of recombinant human manganese superoxide dismutase(rhMn-SOD) against oxidative stress in mice induced by ultraviolet-A(UV-A).METHODS Sixty Kunming male mice were randomly divided into 6 groups: the control group and the model group,injected with 0.9% normal saline(NS),and the native Cu,Zn-SOD group and three doses of the rhMn-SOD trial groups,injected with relevant SOD,respectively.One hour after injection,all the mice were exposed to UV-A for 4 h during 9 d.In d 10 they were killed.The content of malondialdehyde(MDA),the activities of glutathione peroxidase(GSH-Px) and total superoxide dismutase(SOD) in liver,brain and RBC were determined.RESULTS Three antioxidative parameters in the liver and brain of the model group were significantly different(P<0.05)from those of the control group,proving the oxidative injury induced by UV-A on the mice's liver and brain.The oxidative injury induced by UV-A on the liver of experimental mice were obviously reversed by rhMn-SOD in a dose dependent manner(P<0.05).But the difference in three parameters of RBC among 6 groups were no significant(P>0.05).CONCLUSION The oxidative injury on the liver and brain of experimental mice can be induced by UV-A except RBC.The rhMn-SOD has an effective protection on the liver against this oxidative injury induced by UV-A.