Dieulafoy lesion is an uncommon cause of acute gastrointestinal bleeding. The diagnosis is usually carried out endoscopically. We report a 77-year-old woman with rectal Dieulafoy lesion. A recent endoscopic examination missed the lesion because it was small and the bleeding was intermittent. In our case, prompt colonoscopic therapy was allowed after locating the bleeder by multidetector-row computed tomography. On the basis of the success of this procedure, we suggest that an emergent multidetector-row computed tomography could have a role in the management of patients with massive lower gastrointestinal bleeding.