Multiple lymphomatous polyposis (MLP) is a rare condition in which non-Hodgkin lymphoma (NHL), typically mantle cell lymphoma, presents as multiple mucosal polyps of the intestine. We present the case of a 66-year-old man who presented with newly acquired polyps throughout the colon, detected by endoscopy. Endoscopic biopsies confirmed the diagnosis of mantle cell lymphoma. The patient underwent treatment on a research protocol. Our case illustrates the importance of considering MLP or other forms of NHL in elderly patients found to have multiple gastrointestinal polyps, especially those who have a history of clear colonoscopy within the previous one to two years.