Introduction: Healing wounds are characterized by high lactate levels. In the past, the shift to an anaerobic energy metabolism was thought to be the main source for increased lactate concentration. Lactate is also generated by leukocytic NADPH-linked oxygenase using oxygen and glucose as one of its substrates, a mechanism called aerobic glycolysis. We hypothesize that hyperbaric oxygen therapy by increasing oxygen availability enhances wound lactate production by aerobic glycolysis. Material and methods: Four wire mesh wound cylinders (n = 142) were implanted underneath the dorsal skin in each of 36 male Sprague-Dawley rats (312 ± 11 g). Animals were randomized to two groups: The first group (n = 18) received 100% oxygen with 2.1 ATA for 90 minutes twice a day for a total of 7 days. The second group (n = 18) was treated with 21% oxygen with 1 ATA for the same time schedule. Hyperbaric treatments were administered in a hyperbaric chamber designed for small animals. Wound fluid from the cylinders was aspirated between the two treatment cycles at day 2 and 5 and analysed for lactate using a lactate analyser. Additionally, at day 10 (after 2 days of treatment with 21% oxygen in 1 ATA in both groups) lactate concentrations in wound fluid were measured again. Data are expressed as mean ± SD. A p-value <0.05 was considered significant. Results: Wound lactate concentration was significantly increased both in control and hyperbaric rats at day 5 and day 10 compared to day 2 (controls 4.5 ± 1, 5.9 ± 0.8, 6.7 ± 1.2 mmol/l; p = 0.04 and hyperbarics 4.4 ± 1.2, 6.5 ± 1.3, 8.2 ± 1.3 mmol/l; p = 0.01). At day 2 and day 5 there was no significant difference in lactate levels between control and hyperbaric rats. However, at day 10 lactate concentration was significantly higher in the hyperbaric group compared to the control group (6.7 ± 1.2 vs. 8.2 ± 1.3 mmol/l; p = 0.01). Conclusion: This investigation provides evidence for the mechanism of hyperbaric oxygen action since lactate is known to stimulate collagen production and angiogenesis.