Echoencephalograms were obtained for 118 of 121 successive infants who were admitted to the Stanford intensive care nursery, weighed 1,000 g or less at birth, and survived long enough for at least one study to be performed. Eighty-eight of these infants survived and were followed up for 1 to 3 years; psychometric testing (Bayley Scales of Infant Development, Stanford-Binet Intelligence Scale, or both) was performed on 81% of these infants. Subependymal-intraventricular hemorrhages or intraparenchymal hemorrhages were associated with impaired development, but ventriculomegaly was not. The absence of echoencephalographic abnormalities did not exclude the possibility of impaired development in many infants. Periventricular leukomalacia was not observed. These data support independent scoring of subependymal-intraventricular hemorrhages, intraparenchymal hemorrhages, and ventriculomegaly, rather than use of combined scales for prognostic purposes.