A study was performed to investigate the relationship between external and middle ear factors and hearing screening results by auditory brain stem response (ABR) and transient evoked otoacoustic emissions (EOAEs). The ears of 200 well newborns aged 5 hours to 48 hours underwent screening by ABR and EOAEs, followed by otoscopic examination. The pass rates for ABR and EOAE screening were 88.5% and 79%, respectively. On otoscopic examination, 13% (53 of 400) ears had occluding vernix obscuring the view of the tympanic membrane. Cleaning of vernix was attempted in ears that failed ABR or EOAE screening. Seventeen ears that failed ABR were cleaned, and 12 (71%) of them passed repeat ABR. Thirty-three ears that failed EOAE screening were cleaned, and 22 (67%) of them passed repeat emissions testing. Cleaning vernix increased the pass rates for ABR and EOAE screening to 91.5% and 84%, respectively. Decreased tympanic membrane mobility was found in 9% of ears that could be evaluated otoscopically. Increased failure rates for both ABR and EOAE screening were found in infant ears with decreased tympanic membrane mobility, but significance testing could not be performed because of inadequate sample size. Prevalence of occluding external canal vernix and middle ear effusion as a function of increasing infant age were studied. Implications for newborn hearing screening are discussed.