Very preterm birth (before 33 weeks gestation) is associated with the white matter damage, and a common sequel is reduced size and altered shape of the corpus callosum. We used diffusion tensor MRI to assess the corpus callosum in 63 very preterm and 45 term-born young adults. Indices of white matter microstructure [fractional anisotropy (FA) and mean diffusivity (MD)] were obtained for the genu, body and splenium. Very preterm females had higher MD in the genu than term-born females, indicating altered white matter microstructure. This was associated with lower performance la The groups demonstrated different patterns of correlations between verbal learning and tract-specific FA and MD, consistent with the reorganization of white matter structure in adults born very preterm. NeuroReport 20:424-428 (C) 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins.