AimsContinuous positive airway pressure (CPAP) has been used for the prevention and treatment of neonatal respiratory distress for over four decades, but it remains very poorly understood whether there is any brainstem auditory abnormality in babies treated with CPAP. We aimed to detect brainstem auditory abnormality at 34–35 weeks of corrected age in preterm babies treated with CPAP and define any difference between different durations of CPAP treatment. Study designPreterm babies were recruited and dichotomized to those with CPAP treatment (CPAP group, n = 67) and those without CPAP treatment (n-CPAP group) (n = 49). Brainstem auditory evoked response (BAER) was studied at 34–35 weeks of corrected age. ResultsCompared with the n-CPAP group, the CPAP group manifested moderately elevated BAER threshold and significantly prolonged latencies of BAER waves III and V and I-V interval. The prolongation was generally more significant in the babies with longer duration of CPAP treatment than those with shorter duration. The I-V interval in the babies with CPAP treatment for >30 days were significantly longer than those with fewer days of CPAP treatment. ConclusionAt 34–35 weeks of corrected age, preterm babies treated with CPAP are associated with moderate auditory abnormality. Further study is warranted to explore more detail of the auditory abnormality in babies treated with CPAP.