A clinicopathological study was conducted in 19 cases (including 9 autopsied) of midbrain corectopia (oval pupil) occurring in the acute stage of cerebrovascular disorders. This ocular symptom manifested itself in conjunction with severe impairment of consciousness invariably in all instances, unilaterally in 11 and bilaterally in 8 cases, with the shape of the pupil and the direction of its displacement varying from case to case. In 17 cases, this patients died several hours to several days after the appearance of this sign. On autopsy were noted small hemorrhagic lesion of the upper mesencephalic tegmentum in 2 cases and conspicuous cerebral herniation in 7 cases. In this study, it was thought that all cases had diffuse lesions including nuclear, infra- and/or supra-nuclear parts of the midbrain. Clinicopathologically, it was difficult to define the corresponding lesion for corectopia. We suggested that this ocular symptom which appeared transiently was the sign of poor prognosis.