<p><b>OBJECTIVE</b>To study the expression pattern of peroxisome proliferator-activated receptor (PPAR) pathway molecules in ratlungtissue under hyperbaric oxygen exposure.</p><p><b>METHODS</b>Twenty seven male SD rats were randomly divided into hyperbaric normoxia group (0.23 MPa air), hyperbaric oxygentreatmenttime series group (0.23 MPa oxygen, were exposed for 2 h, 4 h, 6 h or 8 h), continuous small flow of ventilation to maintain cabin O2 concentration > 99%. HE staining of lungtissue morphological changes and application oligo microarray to each time point lung were observed. Part of the PPAR pathway genes were validated by RT-PCR.</p><p><b>RESULTS</b>Compared with hyperbaric normoxia group, the lung injury caused by hyperbaric oxygentreatment gradually deteriorated during the time series. Expression microarray analysis of gene ontology (Go) enrichment analysis results in a class of PPAR pathway class included multiple PPAR pathway molecule. RT-PCR results suggested that PPAR-8 and PPAR-Y were up-regulated in the lungtissue after a long time exposure to hyperbaric oxygen.</p><p><b>CONCLUSION</b>Pro-longed hyperbaric oxygen exposure causing pulmonary oxygentoxicity can induce the activation of the PPAR pathway.</p>