Background:　Hyperbaric　oxygen　therapy　(HBOT)　has　been　widely　used　in　the　clinical　setting.　In　this　study,　HBOT　therapy　was　evaluated　for　its　ability　to　ameliorate　the　epithelial-to-mesenchymal　transition　(EMT)　phenomenon　in　keloid　tissue.　Methods:　Keloid　patients　were　randomly　divided　into　two　groups:　keloid　patients　(K　group,　9　patients)　and　keloid　patients　receiving　HBOT　(O　group,　9　patients).　A　third　group　with　normal　skin　(S　group,　9　patients)　was　established　for　control.　Before　HBOT　and　surgery,　a　laser　Doppler　flowmeter　was　used　to　measure　the　keloid　blood　supply　of　patients　in　the　O　group.　Hematoxylin　and　eosin　(H&E)　staining　was　used　to　observe　morphology.　E-cadherin,　ZO-1,　vimentin,　fibronectin,　vascular　endothelial　growth　factor　(VEGF),　and　hypoxia　inducible　factor　(HIF)-1　alpha　were　measured　by　immunofluorescence　staining　and　Western　blot　analysis.　Real-time　quantitative　polymerase　chain　reaction　(RT-qPCR)　was　used　to　evaluate　the　mRNA　expression　level　of　these　factors　as　well.　Results:　In　the　O　group,　keloid　blood　perfusion　was　significantly　reduced　after　patients　received　HBOT.　Compared　with　the　K　group,　lower　expression　levels　of　vimentin,　vibronectin,　VEGF,　and　HIF-1　alpha　were　observed　in　the　O　group,　whereas　the　expression　of　E-cadherin　and　ZO-1　was　significantly　higher.　The　mRNA　expression　of　E-cadherin　and　ZO-1　was　also　increased　after　HBOT.　Conclusions:　The　expression　levels　of　factors　related　to　the　EMT　phenomenon　were　significantly　reversed　in　keloid　patients　after　they　received　HBOT,　indicating　that　HBOT　may　be　an　effective　therapy　against　the　EMT　phenomenon　in　keloid　patients.