We report the case of a duodenal varix rupture in a 37-year-old man revealing an alcoholic cirrhosis. Endoscopic diagnosis of this duodenal varix was difficult because of its atypical and changing appearance. Endoscopic sclerotherapy was completely successful and there was no recurrent bleeding. Although duodenal varix is rare, this case and the literature emphasize the importance of considering this diagnosis in all patients with duodenal tumoral lesions and suspected portal hypertension. In this context, duodenal biopsy can be dangerous and should be avoided. In case of duodenal varix rupture, endoscopic sclerotherapy appears to be a safe and efficient first-choice therapy.