Objectives: In this study, we measured hearing thresholds in patients diagnosed with hyperthyroidism or hypothyroidism with high-frequency audiometry and otoacoustic emission before and after treatment to determine whether hearing losses were cochlear or retrocochlear and whether they would improve with medical therapy. Materials and Methods: This study was conducted on patients diagnosed with hyperthyroidism and hypothyroidism at Cumhuriyet University, Faculty of Medicine, Department of Endocrinology and Metabolism and accepting to participate in the study. We measured the hearing thresholds of the study population during the pretreatment period and in posttreatment euthyroid period. Result: The audiometric findings of patients with hyperthyroidism were better than those of the control group especially at high frequencies. Sensorineural hearing loss was detected in the euthyroid period. We compared the audiometric findings of the patients with hypothyroidism and the controls. We found sensorineural hearing loss in patients with hypothyroidism, especially at low frequencies. Conclusions: The results of this study showed that both hyperthyroidism and hypothyroidism may have an effect on hearing pathway disorders. Medical therapy may lead to hearing loss in patients with hyperthyroidism, and the underlying factors should be investigated in detailed future studies. It was shown in our study that the hearing loss induced by hypothyroidism may improve with medical therapy. Therefore, in all patients with thyroid dysfunction, hearing levels should be monitored closely with audiometric tests.