Brainstem strokes affecting the periaqueductal gray matter of the midbrain can cause vertical ophthalmoplegia. Accompanying clinical features are frequently associated and reflect the involvement of other brainstem structures. We report on an adolescent presenting with vertical gaze palsy and left mydriatic pupil as the only clinical expression of a small infarct located in the left periaqueductal gray matter. Even when the lesion was strictly unilateral, vertical ophthalmoplegia affected both eyes.