Objective To observe the activity of superoxide dismutase（SOD） in rabbit periodontitis model in normoxia and hypoxia environment, and to research the pathogenesis of periodontal diseases at high altitude. Methods Fourty male rabbits were randomly divided into four groups: Normoxia control group, normoxia periodontitis group（periodontitis models）, hypoxia control group, hypoxia periodontitis group（periodontitis models）. The periodontitis models were established by ligating the two central incisors of mandible and raised by periodontitis diets. The weights of four groups were dynamically observed. After eight weeks, the clinical periodontal indexes and the activity of total-SOD（TSOD） in blood serum and gingival tissues in all groups were detected. Results The activity of T-SOD of hypoxia periodontitis group was significantly lower than normoxia periodontitis group and hypoxia control group（P＜0.05）, the weights and clinical periodontal indexes were also dramatically different（P＜0.01）. The activity of SOD in serum was positively correlated with the gingival tissues（r=0.846, P
