Background: Children treated with platinum chemotherapy agents such as cisplatin and carboplatin are at risk for developing irreversible sensorineural hearing loss. Carboplatin ototoxicity is less prevalent than cisplatin ototoxicity, except when used in high doses. Objective: We sought to investigate risk factors associated with ototoxicity in high dose carboplatin hematopoietic stem cell transplantation (cHSCT) in a pediatric population. Study Design: We accepted audiograms with a minimum requirement of threshold data at 4 kHz in at least one ear, allowing us to assess younger, more difficult to test patients and focus on hearing losses at important speech frequencies that can benefit from amplification. Eligible subjects underwent an autologous cHSCT at our institution from 1/1/2008 – 6/30/2022. Three audiologic outcome measures were evaluated – worsening in SIOP grade, significant change in hearing, and ototoxicity. Results: Forty-three cHSCTs from 29 patients had sufficient audiologic data. Logistic regression analysis revealed that cumulative dose of prior cisplatin (OR = 1.01, 95% CI = 1.002-1.014, p = 0.011), and cumulative dose of carboplatin in the preparative regimen (OR = 1.003, 95% CI = 1.001-1.004, p = 0.001), were associated with ototoxicity. Concurrent furosemide with carboplatin administration resulted in 100% ototoxicity, with patients demonstrating a mean change in SIOP grades by 2.0 SE + .038. Conclusion: This report demonstrates that concomitant furosemide administration with carboplatin in cHSCT is associated with ototoxicity, made possible, using criterion that allowed for evaluation of very young children. Further investigations capturing very young patients is needed.