The technique of ABR testing was applied to 25 infants with neonatal hyperbilirubinemia at levels exceeding that for exchange transfusion, in an attempt to study potential influence of bilirubin toxicity on the auditory brainstem pathway. The test was performed at a mean conceptional age of 40.4 +/- 0.6 weeks just after discharge. Twenty normal term neonates of comparable birth weights and conceptional ages, who had no hyperbilirubinemia, were also examined for