Recent studies have shown that intraoperative blood loss and blood transfusions promote postoperative recurrence of hepatocellular carcinoma (HCC). Hyperbaric oxygen therapy (HBOT) is a specific method of oxygen administration, which is independent of fluid therapy or blood transfusion. The aim of the present study was to assess the usefulness of acute HBOT after liver resection for patients with HCC in order to minimize the requirement for perioperative blood transfusions. Forty-one consecutive patients who showed Hb level < 9.0 mg/dl at the end of hepatic resection were randomly assigned to a control group (n = 21) or an HBOT group (n = 20). HBOT at 2.0 atm. with inhalation of 100% oxygen for a duration of 60 min was performed at 3, 24, and/or 48 h after the end of the hepatectomy. Regarding postoperative hepatic hemodynamics, liver function tests, and outcome data, prospective comparisons were completed in both groups. The two groups of patients were similar with respect to results from preoperative assessments. In six patients from the HBOT group, who experienced intraoperative major bleeding or showed fatal hepatic hypoxia (ShvO(2) < 50%), the levels of ShvO(2) and serum lactate were significantly improved after HBOT. When compared to the control group, the HBOT group showed better changes of ShvO(2), serum lactate, and bilirubin levels for the first 3 postoperative days following surgery. Additionally, the HBOT group did not experience any fatal complications and had a lower incidence of postoperative hyperbilirubinemia than the control group. We also observed that postoperative NK cell activity and cancer-free survival in the HBOT group tended to be better than in the control group, although the differences did not reach significance. These results suggest that acute HBOT after hepatectomy, aimed at reducing perioperative erythrocyte transfusions, may be employed for overcoming deficiencies in systemic and hepatic oxygen supply and thus diminishing postoperative complications. As an added benefit, such therapy may affect postoperative immunological responses and long-term survival after liver resection in HCC patients. Further analyses of the use of HBOT is warranted to confirm surgical outcome data and to assess the economic impact on healthcare costs. Ueno, Sakoda, Kurahara, Iino, Minami, Ando, Mataki, Maemura, (2011). Safety and efficacy of early postoperative hyperbaric oxygen therapy with restriction of transfusions in patients with HCC who have undergone partial hepatectomy.¬†Langenbeck’s archives of surgery, 2011 Jan;396(1):99-106.¬†https://www.ncbi.nlm.nih.gov/pubmed/21069381