Four cases of acute arterial occlusion of the lower extremity associated with massive ischemic myopathy and myoglobinuria are reported. Clinically, there were four characteristic manifestations: excruciating pain; severe and extensive ischemia of the tissues; rigidity of the extremity with stiffness of joints; and massive edema. The widespread ischemic myopathy of the extremity is a probable underlying cause of the severity of the local signs. Myoglobinuria was found in the four cases and accounts for the fatal tubular necrosis (myoglobinuric nephrosis) in two patients.