Hyperbaric oxygen therapy (HBOT) could inhibit glioma cell proliferation and inflammatory cell infiltration, and exert a sensitizing effect on ACNU therapy partially through enhancing oxygen pressure (PO2) in tumor tissues and lower expression levels of HIF‐1α, TNF‐α, IL‐1β, VEGF, MMP9, and NF‐κB. This evidence concerns the gene MMP9 and glioma.