The aim of this paper is to analyze and discuss an infrequent topic, i. e. rare conditions of gastrointestinal bleeding.Bleeding from gastrointestinal system is a common cause of acute abdomen and the most frequent causes are generally known.Clinicians, first of all emergency medicine staff, surgeons and internists (gastroenterology specialists), general practitioners, or less frequently other specialists, sometimes meet with less common causes of acute or chronic bleeding from gastrointestinal organs. It is quite important to be aware of the possibility the bleeding being caused by some rare condition, which is not so often met in medical practice, because of their great diagnostic and therapeutic problem. The low index of expectation of such a rare etiological unit could be the reason why destiny of such patients can be extremely problematic and why clinicians may fail at management of these patients (Fig. 4, Ref. 8).