Objective: This study aimed to assess the prognostic value of early posttreatment initiation audiometry findings in patients with idiopathic sudden sensorineural hearing loss (ISSHL)., Study Design: A retrospective cohort study., Setting: The study was conducted at a single tertiary medical center., Methods: A review was conducted on 299 ISSHL patients treated between 2007 and 2023. Patients underwent audiometry on Days 2 to 3 and 5 to 7 posttreatment initiation. Data on demographics, medical history, audiometry results, and prognosis were collected. Prognosis was categorized based on hearing recovery at 1 year postdiagnosis., Results: Older age, worse initial speech reception threshold (SRT), ischemic heart disease, cerebrovascular accidents/transient ischemic attacks, hypertension, and diabetes were associated with a poorer prognosis. Posttreatment initiation audiometry findings on Days 2 to 3 and 5 to 7 significantly correlated with prognosis. Patients with a ≥30% improvement had substantial or complete recovery in over 80% of cases, while those with <10% had <30% recovery. Multivariate analysis identified a significant improvement on days 5 to 7 as an independent predictor of complete recovery (odds ratio = 4.25 [95% confidence interval 1.96-9.23], P = .0002)., Conclusion: Posttreatment initiation audiometry findings, particularly on Days 5 to 7, hold significant prognostic value in ISSHL patients. A substantial improvement during this timeframe is strongly associated with favorable outcomes. These findings emphasize the potential of posttreatment initiation audiometry as a valuable tool for clinicians in counseling patients with ISSHL., (© 2024 The Author(s). Otolaryngology–Head and Neck Surgery published by Wiley Periodicals LLC on behalf of American Academy of Otolaryngology–Head and Neck Surgery Foundation.)