Multimodality-evoked potentials are widely used in newborns to assess the maturation and integrity of the sensory pathways. Reliable normative data are needed to maximize the utility of this technique as a diagnostic and research tool. Several electrophysiologic studies on the maturational changes of the auditory brain-stem response have demonstrated that latency measurements decrease as a function of increasing conceptional age. However, maturational studies of the somatosensory-evoked potential, particularly in low-risk premature infants, are limited. The existing evoked potential literature in healthy newborns proposes that maturation of the central nervous system occurs at a predictable rate, irrespective of a given gestational age at birth. Behavioral studies of premature infants suggest that neurologic development may be altered by early extrauterine exposure. The purpose of this study was to determine whether brain-stem auditory- or somatosensory-evoked potential conduction times were comparable in premature and full-term infants matched for conceptional age. The results of this study suggest that myelination is determined by conceptional age, independent of premature birth.