AIM:To study whether salidroside plays a protective role in hypoxia-induced pulmonary hyperten-sion by suppressing oxidative stress.METHODS: Sprague-Dawley rats were randomly divided into 4 groups: normoxia (N)group,hypoxia for 4 weeks(H4)group,low-dose salidroside(hypoxia for 4 weeks and treatment with salidroside at 16 mg/kg,H4S16)group and high-dose salidroside(hypoxia for 4 weeks and treatment with salidroside at 32 mg/kg, H4S32)group.The mean pulmonary arterial pressure(mPAP), the weight ratio of right ventricle/(left ventricle+sep-tum)[RV/(LV+S)]and vessel wall area/vessel total area(WA/TA)were evaluated.The levels of malondialdehyde (MDA)in the serum and lung tissues were detected by colorimetric method.The levels of 8-iso-prostaglandin F2α(8-iso-PGF2α)in the serum and lung tissues were measured by ELISA.The activity of superoxide dismutase(SOD)in the serum was analyzed by hydroxylamine method.The expression of NAPDH oxidase 4(NOX4)and SOD1 in the lung tissues was determined by Western blot.RESULTS:Compared with N group,the levels of mPAP,RV/(LV+S)and WA/TA in H4 group were significantly increased,which were apparently attenuated by salidroside injection in a dose-dependent manner. Meanwhile,salidroside administration apparently decreased the levels of MDA and 8-iso-PGF2αin the serum and lung tis-sues,as well as the expression of NOX 4 in the lung tissues.Besides,compared with N group, the activity of SOD in the serum and the expression of SOD1 in the lung tissues in H4group were significantly decreased,while administration of sali-droside increased the activity of SOD in the serum and the expression of SOD 1 in the lung tissues in a dose-dependent man-ner.CONCLUSION:Salidroside protects the pulmonary vessels from remodeling and attenuates hypoxia -induced pulmo-nary hypertension by inhibiting oxidative stress.