Background/aim: Studies on the epidemiology of rectal bleeding in children are limited in Iran. Our aim was to assess etiologies of rectal bleeding in children in Iran. Materials and methods: We enrolled 730 children with rectal bleeding. All the patients underwent colonoscopy, and 457 were further evaluated with histopathology. Results: According to colonoscopy and histopathology, respectively, in ammatory bowel disease (IBD) (29.4%, 15.8%), nodular hyperplasia (NH) (24.9%, 10%), and juvenile polyposis (JP) (12.6%, 9.9%) were the most common causes of rectal bleeding. Other conditions were solitary rectal ulcer (5.3%), chronic colitis (4.6%), allergic colitis (3.3%), focal colitis (1.3%), and infectious colitis (1.1%). In colonoscopy, there were no signi cant di erences in the distribution of pathologies regarding sex, while the youngest and oldest mean ages were found for patients with NH (4.6 &pm; 3.9 years, P < 0.0001) and those with normal appearance (8.1 &pm; 4.4 years, P < 0.0001) respectively. Based on histopathologic reports, the youngest patients were diagnosed with infectious colitis (4.6 &pm; 2.8 years), while patients with chronic colitis were the oldest (9.2 &pm; 4.6 years, P = 0.003). Conclusion: JP, NH, and IBD constituted the most common etiologies of rectal bleeding in our patients. It is recommended to perform a complete diagnostic approach to accurately assess rectal bleeding in children.