The effects of hyperbaric oxygen therapy on skin microcirculation were evaluated by laser-Doppler flowmetry and vital capillary microscopy in a frostbite victim 2 wk after the injury. Laser-Doppler skin blood flow, measured in intact skin on the dorsum of the foot, decreased from 52 to 31 perfusion units during hyperbaric oxygen therapy. The number of visible nutritive capillaries in frostbitten areas on the toes increased from 2 to 12 per mm2, as measured immediately after the hyperbaric oxygen therapy. We conclude that hyperbaric oxygen therapy is capable of improving nutritive skin blood flow in frostbitten areas more than 2 wk after the injury.