Small-bowel lymphoma is not a common disease, accounting for 15-20% of primary extranodal gastrointestinal lymphomas. Peritoneal lymphomatosis is considered a rare and aggressive presentation. We describe the case of a 55 years-old man affected by T-cell intestinal lymphoma, presenting with diffuse abdominal involvement, bowel dysfunction, severe ascites and pleural effusion, who underwent surgery. Clinical course led dramatically to death. Preoperative cytology and radiologic investigations did not yield diagnosis and were unable to differentiate between peritoneal carcinosis and lymphomatosis. It is suggested that, in such advanced cases, with rapidly deteriorating clinical conditions and huge systemic involvement, surgery is not indicated. On the contrary, maximum effort has to be spent to obtain a preoperative diagnosis.