Upper gastrointestinal system bleeding should be first taken into account when a patient complains of melena. On rare occasions, gastrointestinal bleeding may be due to primary or metastatic tumors of the gastrointestinal system. Here, we present a case in which the localization of bleeding was demonstrated by Tc-99m red blood cell labeled scintigraphy with the final diagnosis of metastases of non-small cell lung cancer to the small bowel.