AbstractReduced posterior corpus callosum (CC) area has been consistently observed in children and adolescents born very preterm (VPT). CC structural differences are also observed in people diagnosed with empathy disorders. This study examined empathy in relation to CC size in VPT adults and controls. CC area was manually measured for 17 VPT adults and 9 controls. Participants completed the Interpersonal Reactivity Index (Davis, 1980) and the Empathy Quotient (Baron-Cohen & Wheelwright, 2004). VPT adults had reduced posterior CC area in contrast to controls, and a positive linear trend was observed between posterior CC size and gestational age. No between-group empathy differences were observed, although self-reported personal distress in response to social situations was higher in VPT adults, and negatively associated with anterior CC area. We conclude that VPT adults have a smaller posterior CC, which is associated with gestational age, and elevated social distress, which may be mediated by anterior CC size. (JINS, 2010, 16, 716–720.)