BACKGROUND Cyanotic congenital heart diseases usually lead to growth and developmental delay in children due to chronic hypoxemia and undernourishment that may affect the central nervous system. The auditory brainstem responses are determined to assess the maturation and function of the brainstem. Therefore, we used the auditory brainstem responses to investigate the effect of cyanotic congenital heart diseases on brainstem maturation. METHODS The auditory brainstem responses were investigated in 45 children (23 cyanotic, 22 acyanotic) with congenital heart diseases and compared with the results of 30 healthy counterparts (all children were aged between 2 months and 15 years). RESULTS The results of auditory brainstem responses were similar in acyanotic patients and in normal children. The cyanotic patients under 1 year of age had more prolonged I-V interpeak latencies than those of control and acyanotic patients (P < 0.05). There was no difference between all groups older than 1 year of age. In cyanotic children, I-V interpeak latencies showed significant negative correlation with arterial oxygen saturation and partial oxygen pressure (P < 0.05). CONCLUSIONS Cyanotic congenital heart diseases may cause significant retardation on brainstem maturation due to chronic hypoxemia, especially in infants under 1 year of age, whereas acyanotic congenital heart diseases have no effect on auditory brainstem responses.