To clarify the characteristics and diagnostic value of yperventilation-induced nystagmus (HIN) in cerebellopontine angle (CPA) tumors. Early detection of CPA tumor is important for perioperative reservation of hearing and facial nerve function. HIN has been observed in patients with CPA tumors as well as other peripheral vestibulopathies. Defining the characteristics of HIN in CPA tumors may provide a diagnostic clue for differentiating more devastating CPA tumors from other benign peripheral vestibular disorders.