Background Upper gastrointestinal bleeding is a life-threatening emergency. Endoscopy is the therapeutic and diagnostic procedure of choice after initial stabilization of the patient. But the presence of retained blood, blood products, and other residual material in the stomach is a big challenge for endoscopists during urgent endoscopy after acute upper gastrointestinal bleeding. Intravenous erythromycin before endoscopy improves the visualization of gastric and duodenal mucosa in these patients. Use of oral erythromycin is more easy and convenient, so the objective of our study was to assess the effects of oral erythromycin on quality of endoscopy in upper gastrointestinal bleeding patients.