Background: The application of mechanical ventilation to the newborn has presumably allowed the survival of seriously ill infants who would previously have died, and who have had a variety of illnesses, not necessarily primarily respiratory. It could represent a new source of childhood handicap, it seems important to determine its extent and severity in a neonatal intensive care referral unit. This study was aimed to evaluate the effect of invasive ventilation (SIMV) and non invasive ventilation (NCPAP) on auditory functions in preterm infants (23 to 37weeks). Patients and methods: This retrospective cohort study included thirty preterm infants attending in NICU. All patients were subjected to the full history taking, physical examination and Visual examination of the external auditory meatus and tympanic membrane was performed using a Welch Allyn Halogen Otoscope. The patients were followed up for each complication. Results: There was an increase in CS mode in NCPAP group (86.7%) compared to 40% in SIMV group had been delivered by CS mode) and non-significant difference between them regarding presence of maternal risk factors. The relation between type of ventilation and mode of deliver. There was significant increase in APGAR score over time in both groups. There was a significant increase of hemoglobin in SIMV group , increase of total bilirubin NCPAP group and increase of AST in SIMV group. There is non-significant difference between the studied groups regarding WBCS, platelet count, CRP, direct bilirubin, or ALT. There was a significant increase of PCO2 in SIMV group and no significant difference between the studied groups regarding PH, PO2 or HCO3. There was a significant increase in duration of admission in SIMV group. There is statistically non-significant difference between the studied groups regarding result of OME or ABR. One patient within SIMV group had partially passed OME while on doing ABR, it became normal Conclusion: SIMV and NCPAP revealed no significant differences on the auditory function of preterm infants. Keywords: Preterm Infants Invasive Ventilation; Non-Invasive Ventilation; Neonates