Eleven congenital hypothyroid newborns were consecutively referred for audiological evaluation before any treatment. Evoked otoacoustic emissions were present bilaterally in 9 newborns. These results suggest the normality outer hair cells and contrast with results obtained in experimental studies. The auditory brainstem responses in 6 newborns showed a prolonged wave I, as previously reported by other authors. At 9 to 12 months of age, all children treated had evoked otoacoustic emissions in at least one ear. In 9 cases, the auditory threshold was normal (equal to or below 20 dB) as determined by behavioural tests.