Materials and Methods: In 20 patients diagnosed with severe generalized chronic periodontitis (pockets>7mm) with bleeding on probing, SRP was rendered in all pockets. Additionally, five consecutive hyperbaric sessions were administered in 10 patients after random allocation (SRP+HBOT). Clinical parameters were assessed at baseline up to 6 months: plaque index (PI), bleeding on probing, probing depth, clinical attachment level and BANA test.