Background Iron deficiency anemia (IDA) in late adolescent women has multiple pathophysiologies. Silent blood loss, celiac disease (CD), malignancies, and other gastrointestinal (GI) lesions receive much attention during IDA management. There is no consensus about endoscopic screening. Our study evaluates factors affecting GI endoscopic diagnosis for the etiology of IDA in late adolescent women. Materials and Methods We conducted an observational, multicenter retrospective analysis of 192 adolescent women with IDA admitted for GI endoscopic diagnosis from 2006 to 2016. Baseline measurements included hemoglobin, serum ferritin, mean corpuscular volume, serum iron, total iron-binding capacity, and transferrin saturation. We collected demographic characteristics, duration of hospital stay, the degree of severity of anemia, and endoscopic findings. Results The mean age was 19±1 years (range 17 to 21 years), with mildly to moderately severe IDA. Patients received esophagogastroduodenoscopy (EGD, n=178) or colonoscopy (n=14). The mean hospital stay was 2.0±1.0 days. We found negative endoscopies (n=74), CD (n=85), gastric ulcer (n=19), malignancy (n=2), inflammatory bowel disease (n=1), and other nonsignificant endoscopic findings (n=11). We found no correlation between the duration of the hospital stay with the severity of IDA, no significant association between GI symptoms of the patients with endoscopic findings, and a significant but weak association between GI symptoms and serum ferritin. Conclusions In late adolescent women with IDA who have significant GI endoscopic lesions, the GI symptoms are of limited value in guiding the endoscopic diagnostic approach for evaluation of IDA.