Background: Anemia is a major world-wide health problem. Iron deficiency anemia (IDA) is a common manifestation of most of the gastrointestinal lesions. Objective: Evaluation of the role of gastrointestinal endoscopy in detecting the causes of iron deficiency anemia. Patients and Methods: Fifty patients with Iron deficiency anemia with no obvious cause participated in this study during the period from April 2019 to October 2020. They presented to the Department of Internal Medicine, Al-Hussein University Hospital, and referred for gastrointestinal endoscopy. Results: Thirty eight patients (76%) of the 50 studied anemic patients had gastrointestinal lesions detected by either esophagogastroduodenoscopy (EGD), or colonoscopy or both of them. Conclusion: Iron deficiency anemia is a common manifestation of most of the gastrointestinal lesion. Gastrointestinal endoscopy is a very valuable investigation in the diagnosis of the causes of iron deficiency anemia.