The development of visual acuity during the first year of life was assessed in 91 normal fullterm infants and 36 preterm infants with minimal perinatal complications, using the forced-choice preferential looking technique. Acuity in the preterm infants lagged behind that of the fullterm infants up to the age of 6-8 months if age was calculated from birth, and then reached equal levels. When age was corrected for prematurity, acuities in the two groups were very similar at all ages, but mean preterm acuity was consistently slightly higher than in the fullterm infants. The results suggest that early visual experience of preterm infants in the period up to the expected date of term may lead to a slight acceleration of the development of behavioural visual acuity. This is discussed in relation to electrophysiological studies which report a greater effect of prematurity on acuity development.