BACKGROUND/AIMS: There is no consensus for the role of endoscopy in the etiologic investigation of iron deficiency anemia (IDA) in Korea. We carried out a retrospective study to evaluate the role of esophagogastroduodenoscopy (EGD) and colonoscopy for their etiologic diagnosis in IDA. METHODS: Between January 1998 and September 2003, 129 patients (male:female=19:110, mean age=43.6) had been grew EGD and colonoscopy for exam for the investigation of IDA at Kangbuk Samsung Hospital and Samsung Medical Center Medical records were retrospectively reviewed: RESULTS: Significant findings were found in 8.5% (11 cases: grade B reflux esophagitis by L.A. classification (1), angiodysplasia (1), severe erosive gastritis (2), and gastric ulcer (2) and duodenal ulcer (5), while 70% (89 cases) showed some abnormality in EGD examination. Significant findings were seen in 11% (14 cases: polyps >1 cm (2), angiodysplasia (1), bleeding hemorrhoids (5), inflammatory bowel disease (4) and colon cancer (2)), among 36% (46 cases) of patients with some abnormality in colonoscopy. CONCLUSIONS: Gastrointestinal lesions were frequently found in patients with IDA and significant proportion of them could be the source of blood loss. Therefore, EGD and colonoscopy should be included in the evaluation of IDA in Korea.