Relative maturation of peripheral and central regions of the neonatal brainstem was studied using brainstem auditory evoked responses in 174 healthy preterm infants (gestational age 30–36 wk). From 30- to 42-wk postconceptional age (PCA), I–III and III–V intervals shortened with increasing age. It was difficult to detect any apparent differences in maturational rate between the two intervals. However, III–V/I–III interval ratio decreased with increasing age, indicating that from preterm to term III–V interval shortens more than I–III interval. During term period (37- to 42-wk PCA), I–III interval was similar to term controls, but III–V interval was significantly longer and III–V/I–III interval ratio was significantly greater than controls at 37- to 38-wk PCA and 39–40 wk PCA and was the same as controls at 41–42 wk. Therefore, from 30- to 42-wk PCA maturation of central regions of the brainstem, reflected by III–V interval, is relatively faster than peripheral regions, reflected by I–III interval which seems to be already more mature than III–V interval before 30 wk. Maturation in central regions in preterm infants is relatively delayed at early term, but “catches-up” later, whereas peripheral regions already reach normal level of maturation at early term. Preterm birth slightly delays early maturation of central brainstem regions.