lntroduction: ln gaslroesophageal reflux disease (GERD), gastric contents rellux back into the esophagus via the lower esophageal sphincter (LES), causing characteristic, distressing symptoms. The incidence in childhood is 0.2-0.5/1000 population. It can occur at any time lrom infancy to adolescence with variable clinical presentation and therapeutic options. An important complication is erosive esophageal inllammation, the severity of which depends on the frequency of reflux episodes and the time elapsed before therapy is initiated. One of the rare manifestations ol gastroesophageal reflux disease is the triad, lirst described by and named aller Herbst and his team in 1976, which is associated with refractory iron deficiency anemia, finger clubbing and protein-losing enteropathy with reflux and hiatal hernia. ln the literature, 17 cases have been reported worldwide. Gase presenlalion: Gase 1: A five-and-a-half-year-old girl with a negative medical history was referred for gastroenterological evaluation because of unimproved regurgitation after 6 months of proton pump inhibitor therapy. Her physical examination and initial laboratory blood tests showed no abnormalities, celiac disease, food allergies were not confirmed serologically. lnitial esophagogastro-duodenoscopy showed severe inflammation (Los Angeles C) in the lower third of the esophagus, and the histologic specimen was suggestive ol eosinophilic esophagitis. Therapy with proton pump inhibitors, sucralfat and inhaled corticosteroids was started, but there was no clinical improvement, follow-up endoscopy showed unchanged findings. ln addition, iron deficiency anemia and hypalbuminemia developed. 0ral and then parenteral iron supplementation was started and systemic steroid therapy was given for one month, but her complaints and laboratory abnormalities did not change significantly. One year after the investigations started, a follow-up endoscopy revealed tubulaf inflamed, pseudopolypoid gastric mucosa under the cardia, raising the possibility ol a hiatal hernia, which was confirmed by ultrasonography. Finger clubbing was also noted at this time. Surgical fundoplication was performed, which improved her clinical symptoms and resolved the anemia and hypalbuminemia, Case 2: The complaints ol the 8-year-old boy bean six months before his admission to our institution with fatigue and dizziness. Physical signs of anemia and hepatomegaly were noted at the beginning of the evaluation. Laboratory tests revealed iron deficiency anemia, which was reversed by transfusion. Abdominal ullrasonography showed mild hepatomegaly. Fecal calprotectin test and specific tests for metabolic disorders were negative. Histopathologic examination of bone marrow showed no abnormal cell proliferation. After one month, he presented with finger clubbing, microcytic anemia and hypalbuminemia. Upper endoscopic examination of the esophagus showed mucosa covered with white plaque, lower endoscopic examination showed intact conditions. He was referred to our institution for further evalualion. Abdominal ultrasonography showed permanent reflux, raising the possibility of a hiatal hernia, which was confirmed by passage assessment in the upper gastrointestinal tract. Pulmonologic examination with lung function test and chest X-ray did not reveal a chronic respiratory origin in the background of the clubbing. Repeated upper endoscopy confirmed severe esophagitis and sliding hiatal hernia. The investigations and clinical presentation fulfilled the criteria for the Herbst triad with underlying gastroesophageal reflux and hiatal hernia. Follow-up laboratory values improved with oral proton pump inhibitor therapy. Laparoscopic fundoplication was performed due to persistent regurgitation, laparoscopic fundoplication was performed. Follow-up endoscopy showed improving findings. Conclusion: Gastroesophageal reflux disease should be considered in the differential diagnosis of persistent iron deficiency anemia, protei