CONCLUSIONS This study showed that patients with acoustic tumor (AT) with hearing loss in the contralateral side had severe mood disturbances. It is important for physicians to provide patients who have better hearing in the tumor side with adequate information regarding the possibility of profound bilateral hearing loss and how to communicate with others in such situations. OBJECTIVES We examined the pretreatment status as regards neurosis and/or depression of patients with an AT using the Cornell Medical Index (CMI) and Self-rating Depression Scale (SDS) and clarified the relationship with the patients' background. METHODS We enrolled 30 patients with unilateral AT between 1997 and 2010. At the time of diagnosis, we examined each patient's psychological condition, sex, age, laterality, tumor size, hearing level on bilateral side, facial paresis, headache, and canal paresis. RESULTS In all, 20.0% of AT patients were diagnosed with neurosis using the CMI and 26.7% had depression according to the SDS. χ(2) analysis showed that patients with AT with hearing deterioration on the contralateral side had mental illness significantly more often than those with normal hearing on the contralateral side. Multivariable regression analysis revealed that the pretreatment status of hearing level on the contralateral side significantly affected the patients' psychological condition.