Background: Moderate to severe acquired sensorineural hearing loss (SNHL) in children is associated with substantial long term neurocognitive morbidity. The underlying cause of SNHL is loss of hair cells in the Organ of Corti. Currently, there are no successful neuro-reparative treatments for SNHL. Numerous pre-clinical studies suggest that cord blood derived mononuclear cells (hUCBC), cells derived from hUCBC, or similar cells derived from bone marrow allow at least partial restoration of SNHL by enabling repair of the damaged Organ of Corti. Objective: To determine whether intravenous autologous cord blood mononuclear fraction is a safe treatment for moderate to severe acquired SNHL in children. Methods: After obtaining IND and IRB approval, eleven children aged 6 months to 6 years with moderate to severe acquired SNHL were treated with autologous cord blood mononuclear fraction delivered intravenously from November of 2013 to February 2016. Cell dose ranged from 8 x 106 to 30 x 106 cells/kg body weight. To determine the safety of the procedure, systemic hemodynamics were monitored during the infusion and post infusion period. Infusion related toxicity was determined by hepatic enzyme, renal function, chest x-rays and oxygen saturation measurements. Auditory function was measured using tympanometry, otoacoustic emission (OAE) testing, auditory brain stem response (ABR) pre-infusion and at one, six and twelve months post-infusion. Auditory Verbal language assessments were obtained pre-infusion and six and twelve month’s post-infusion. Brain MRIs with diffusion tensor sequences were obtained pre-infusion and one year post infusion. The final subject’s one year follow-up was completed in February of 2017. Results: All patients survived, and no adverse events occurred. There was no infusion related depression of systemic hemodynamics. No detectable infusion-related toxicity was recorded. Five subjects experienced a significant reduction in ABR thresholds. Four of the same five patients also experienced a reduction in ABR latencies. The improvements were stable over the duration of the study. Comparison of MRI with DTI sequences obtained before and one year post infusion, revealed increased anisotropy in Heschel’sHerschel’s Gyrus (primary auditory cortex), in three of five subjects with significantly reduced ABR thresholds. Language development was appropriate for subjects who received adequate amplification and speech therapy. Conclusion: Intravenous administration of autologous hUCB for acquired sensorineural hearing loss is feasible and safe in infants and children.