Objective One of the most common brain abnormalities in preterm infants is thinning of the corpus calloisum (CC). Such injury may be partly explained by the vulnerability of the developing CC to hypoxic-ischemic damage and hemorrhage due to intrinsic vulnerability of immature oligodendrocytes. The CC is among the last structures to be completed during postnatal maturation. Several studies have shown a relation between the size of CC and motor outcome in preterm infants. Three-dimensional ultrasound (3D-US) offers new perspectives in cerebral imaging. Methods 43 preterm infants with a gestational age < 32 weeks (wks) were included in this prospective study. With transfontanellar 3D-US measurements were done at 9 different time points (24–26 wks, 27–28 wks, 29–30 wks, 31–32 wks, 33–34 wks, 35–36 wks, 37–43 wks, 44–50 wks, 51–55 wks). Size of rostrum, corpus, splenium and length, circumference and surface area of the CC was assessed. Neurodevelopmental outcome at the age of 5 years was analyzed by Kaufmann's Assessment Battery for Children (K-ABC) and Beery-Buktenica Developmental Test of Visual-Motor Integration (VMI). Results By 3D US reference values for size, length, circumference and surface area of the CC at all different timepoints could be established. The data examined at corrected term age showed a significant correlation of corpus size of CC and visual motor integration (p=0.04) and of circumference and surface area of CC and simultanous processing scale (p=0.01) and mental processing composite (p=0.04) of K-ABC. A trend was seen for the correlation of surface area oft the CC and achievement scale of the K-ABC (p=0.08) and visual perception assessed by VMI (p=0.08). Conclusion Biometry of the CC in preterm infants can sufficiently be done by 3D US. Especially surface area of the CC at corrected term age correlates with later neurodevelopmental outcome.