Dieulafoy lesion is rarely seen, yet it can be life-threatening. This lesion makes up to 1-2% of gastrointestinal bleedings and must definitely be considered in gastrointestinal bleedings whose source cannot be identified. In this case study, the 75-year-old woman was suffering from active, fresh, and massive rectal bleeding. Colonoscopy was applied in order to find out the source of bleeding. In the typical endoscopic appearance of the lesion a single round mucosal defect in the rectum and arterial bleeding were observed. To procure hemostasis, epinephrine was injected into the lesion and the bleeding vein was sutured.