Lately, we have been confronted with an increased number of malignant tumors of the large bowel, appearing at younger patients. Among all histopathologic forms of malignant colonic tumors treated in our Clinic, lymphoma is the fifth as frequency of apparition, respectively the fourth at patients less than 40 years old. We present the case of a 22-years-old patient, having colonic polyposis and multicentric non-Hodgkin lymphoma of the terminal ileum and ascending colon. This pathologic association represented for us an uncommon situation. The rest of malignant colonic tumors developed on patients with rectocolonic polyposis were adenocarcinoma.