Ultrasound brain scans sometimes demonstrate increased echogenicity or cysts, or both, in the periventricular white matter, superolateral to the ventricle, in the most common site of periventricular infarction. Over 33 months, 23 preterm infants dying after 20 or more days of life were entered into this study. Superolateral echogenicity or cysts were found in 13 (57%) cases. Periventricular infarction was present at autopsy in 12 (52%) cases. Ultrasound accurately diagnosed the size, site, and extent of periventricular infarction in 78% of scans. Interpretive errors were made with poor-quality scans and with early and late studies. We conclude that sector ultrasound brain scans accurately diagnose major periventricular infarction. Hemorrhage into the site of infarction is not a prerequisite for diagnosis of periventricular infarction by ultrasound.