OBJECTIVE To investigate the protective effects of hydrogen on renal ischemic/reperfusion injury and its mechanism in rats. METHODS Eighteen adult male Sprague-Dawley rats were used and allocated into sham-operated group (Sham group), ischemic reperfusion group (I/R group) and hydrogen treated group (H2 group) randomly. Ischemic/reperfusion of the left renal pedicles following a right nephrectomy was investigated in I/R group. In the Sham group, the rats were subjected to identical surgical procedure without occlusion of left renal pedicles. In the H2 group, inhalation of the 2.5% hydrogen was initiated 10 min before reperfusion and last for 130 min till the end of the 120-min reperfusion. Plasma level of usea nitrogen (BUN), creatinine (Cr), maiondiaidehyde (MDA), the score of histopathological examination of left kidney were evaluated 24 h after operation in all subjects. RESULTS Ischemia-reperfusion injury rat model was established successfully. Inhalation of hydrogen (2.5%) markedly reduced the level of serum BUN, CREA and MDA (P < 0.05). The histopathological outcome in the H2 group was significantly improved, compared to the I/R group (P < 0.05). CONCLUSIONS Inhalation of hydrogen could attenuate renal ischemic/reperfusion injury in rats by decreasing the content of MDA.