The effects of pressure-induced ischemia on energy metabolism, measured as ATP and glucose content, is studied in hamster cheek pouch. Metabolic deterioration during ischemia is studied and after 2 h the glucose content was significantly reduced but not the ATP content, which was significantly reduced after 4 h of ischemia. Restoration of glucose levels in the cheek pouch tissue was achieved within 30 min of recirculation after release of pressure. The cellular energy metabolism is unable after 4 h of ischemia to restore ATP levels in the tissue during the 120-min of postischemic observation time. There is a difference in ability to resume normal energy metabolism after 2 and 4 h of pressure-induced ischemia.