A 68-year-old man was admitted to our hospital for an acute and isolated anterograde and retrograde amnesia. He had a previous history of diabetes, hypertension, and myocardial infarction but not of alcohol abuse. Cerebral magnetic resonance imaging revealed an isolated infarction of the genu of the corpus callosum and of the bilateral anterior columns of the fornix (Figure 1), corresponding to the subcallosal artery territory, a perforator branch of the anterior communicating artery. There were no associated lacunes or leukoaraiosis on fluid-attenuated inversion recovery sequences. Diffusion tensor tractography (DTT) of the limbic system performed 11 days later showed complete disruption of the corpus callosum genu commissural fibers and severe rarefaction of the fornix bilateral anterior column projection fibers and of the frontal fibers (Figure 2). One year later, our patient still had severe amnesia. There was no new lesion on magnetic resonance imaging.