Objectives: This study aimed to investigate the role of ischemia-modified albumin and thiol/disulfide hemostasis in idiopathic sudden sensorineural hearing loss (ISSNHL). Patients and Methods: This prospective study was conducted with volunteers diagnosed with ISSNHL and healthy individuals between November 2018 and June 2019. The study group included 46 patients (27 males, 19 females; mean age: 42.4±12.3 years; range, 18 to 69 years), and the control group included 41 healthy individuals (25 males, 16 females; mean age: 37.8±11.7 years; range, 18 to 65 years). Serum thiol, disulfide, and ischemia-modified albumin were calculated in ISSNHL patients and control groups. The relationship between prognostic factors of disease and blood values was investigated. Results: The native thiol/total thiol ratio was significantly higher in the control group. Disulfide levels, disulfide/native thiol ratio, and disulfide/total thiol ratio were significantly higher in the patient group. Conclusion: Oxidative stress that is not balanced by an adequate antioxidant defense may play an important role in the etiopathogenesis of ISSNHL.