We investigated the levels of oxygenation in the extended cerebral regions, including the middle cerebral artery region, using optical topography in two patients who underwent total arch replacement assisted by selective cerebral perfusion. During the cooling phase, the oxyhemoglobin levels were almost homogenous. During selective cerebral perfusion, when 18 French and 16 French cannulae were used for the innominate and the left common carotid artery respectively, the oxyhemoglobin levels in the left hemisphere were consistently greater than those in the right. After the 16 French cannula was replaced with a 14 French in the left common carotid artery, then no difference between the hemispheres was found. During the rewarming phase, the increase in the oxyhemoglobin levels in the parietal region was consistently more delayed than that in the temporal region, in both patients. Optical topography might be useful for more precise monitoring of the cerebral circulatory status during an aortic arch operation.