As only a handful of lymphoma cases have been reported in conjunction with primary intestinal lymphangiectasia, it is not yet clear if this association is merely fortuitous or related to primary intestinal lymphangiectasia induced immune deficiency. We report on two female patients, 50 and 58 years old, who developed small intestinal high grade B cell lymphoma a long time (45 and 40 years, respectively) after the initial clinical manifestations of primary intestinal lymphangiectasia. They presented with a longstanding history of fluctuating protein losing enteropathy, multiple cutaneous plane warts, and markedly dilated mucosal and submucosal lymphatic channels in duodenal biopsies. One had a large ulcerated tumour of the proximal ileum and the other diVuse ileal infiltration. In both, histological examination showed centroblastic high grade B cell lymphoma associated with duodenojejuno-ileal mucosal and submucosal lymphangiectasia. They were subsequently successfully treated with surgery and postoperative chemotherapy (AVmCP: adriamycin, cyclophosphamide, Vm26, and prednisolone), and chemotherapy alone (PACOB: adriamycin, cyclophosphamide, vincristine, bleomycine, and prednisolone), respectively. A three year follow up in both cases showed persistent diVuse lymphangiectasia without evidence of lymphoma. The present findings support the hypothesis that primary intestinal lymphangiectasia is associated with lymphoma development.