The aim of the present study using near-infrared spectroscopy (NIRS) is to evaluate the correlation of cerebral (parieto-temporal lobe) hemoglobin changes and vertiginous sensation during unilateral caloric stimulation. During the hot water (44 degrees C) stimulus, cerebral hemoglobin was increased bilaterally, but it was dominant ipsilaterally. During the unilateral cold water (30 degrees C) stimulus, cerebral hemoglobin was decreased on both sides, especially on the ipsilateral side. Vertigious sensation was strong in cases with marked left-right difference of cerebral hemoglobin changes. The usefulness of NIRS to investigate the relationship between peripheral vestibular organ and vestibular cortex was verified.