ObjectiveTo explore the feasibility of medical ozone in treatment of pulmonary fibrosis. MethodsForty Wistar rats were randomly divided into an experimental group and a control group, with 20 rats in each group.All rats were intratreacheally instilled with bleomycin to induce pulmonary fibrosis.Then the rats were intraperitoneally injected with physiological saline every other day in the control group, and with medical ozone every other day in the experimental group.After 28 days, 10 rats in each group were sacrificed after lung function test.Right lung tissues were sampled for pathological examination, and left lung tissues were sampled for measurement of superoxide dismutase (SOD) and hydroxyproline.The remaining 10 rats in each group continued to be normally fed and intraperitoneally injected for observation of the survival time. ResultsThe lung function of the control group significantly decreased compared with the experimental group.The degree of lung fibrosis in the control group was more severe than that in the experimental group (lung fibrosis score: 1.9±0.5 vs.1.2±0.4, P < 0.05). The level of SOD in lung tissue was significantly higher and the level of hydroxyproline was significantly lower in the experimental group compared with the control group [(208.48±29.37)U·mg-1·pro-1 vs.(163.34±21.42) U·mg-1·pro-1, (2.25±0.28) mg/g vs.(2.68±0.37) mg/g, P < 0.05].The rats in the experimental group had longer survival time compared with the control group (79 d vs.59 d, P < 0.05). ConclusionMedical ozone can delay the progress of pulmonary fibrosis in rats.