In this study the maturation of the central nervous system of full-term and premature infants were investigated electrophysiologically. The subjects were 16 full-term and 15 premature infants. Neurologic examination, psychometric tests, and measurement of evoked potentials were carried out periodically in babies who had no birth trauma, metabolic disorder, or intrauterine infection. Neurophysiologic comparison of the results was evaluated. As the babies grew older, I-V interpeak latency became shorter according to the results of brainstem auditory evoked potentials; N₁-P₁ amplitude became higher and P₁ latency shorter according to the results of visual evoked potentials. Central nervous system maturation of full-term babies and prematures appear to be alike at 6 months of age.