The compartment syndrome was described by Von Volkmann in 1872 and numerous reports have since been published. But muscle necrosis associated with carbon monoxide poisoning is a relatively rare, and some authors have been regarded their etiology as hypoxemia and extemal pressure. We experienced a case of acute compartment syndrome in the pectoral fascia due to prolonged compression on the anterior protion of left axilla between a pillow just below axilla and his fellow in C.O. poisoning.