Rationale:Colonic extranodal mucosa-associated lymphoid tissue lymphoma as a cause of hematochezia is rare. Here, we report a case of colonic extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALToma) with presentation of freshy bloody stool and successfully treated by endoscopic mucosal resection.Patient concerns:This case was a 69-year-old woman with history of hypertension, reflux esophagitis, and peptic ulcer. She had several episodes of hematochezia and thus sought medical attention at the outpatient clinic.Diagnoses:Colonoscopy revealed a 12-mm semipedunculated lesion in the ascending colon. Histopathological examination and immunochemistry were compatible with colonic extranodal mucosa-associated lymphoid tissue lymphoma.Interventions:Endoscopic mucosal resection was done for tumor removal and hemoclipping was done to achieve hemostasis.Outcomes:The patient remained well without recurrence during 3 years of outpatient follow-up.Lesson:Colonic MALToma is a rare disease, and could present as hematochezia.En blocendoscopic resection could achieve long-term remission. The prognosis of colonic MALToma is excellent with its indolent characteristics.