The purpose of this study was to evaluate the visual development of preterm infants from 1 to 6 mo of age, using the pattern visual evoked potentials (VEP) in response to three check sizes: 60, 30, and 15 min of arc. Pattern VEP were recorded in 24 full-term and 24 preterm infants (26-36 wk of gestation). The results showed a rapid visual maturation between 1 and 3 mo, followed by a slower progression over the next 3 mo, in both groups. The implicit time of the P100 wave of the pattern VEP was also found to shorten with increasing check sizes. The maturation of pattern VEP in preterm infants was shown to be related to their gestational (or corrected) age rather than their postnatal age. The pattern VEP obtained in response to a 60-min check size in preterm infants aged between 1.5 and 2.5 mo (corrected age) showed a tendency for a faster maturation than those of full-term infants. Our results suggest that within the first 6 mo of age, pattern VEP response is useful to monitor visual development in full-term infants as well as in preterm infants using corrected age.