Brainstem auditory evoked response studies were carried out on 105 neonates, with gestational ages ranging from 26 to 43 weeks. The mean chronologic and postconception ages of the subjects were 6.5 weeks and 40.6 weeks, respectively. Statistically significant relationships between brainstem auditory evoked response and gestational age, postconception age (gestational age plus chronologic age), and the 5-minute Apgar score, were demonstrated. Shortening of brainstem auditory evoked response as related to postconception age was demonstrated and this trend was statistically significant. However, of these factors a statistically significant shortening (maturation) of evoked response was demonstrated only in relation to postconception age.