The authors of this article point out the diagnostic scopes and advantages of the intraoperative endoscopy as one of the many diagnostic means, which may be employed to determine the cause of recurrent attacks of bleeding to the gastrointestinal tract. As an example demonstrating the scope of use of this relatively simple device, they present a case of examining a female patient with the recurrent attacks of bleeding to the gastrointestinal tract. Should other common diagnostic methods be employed, the case of the bleeding was impossible to discover.