The Authors comment on the difficulty of diagnosing and treating duodenal tumours. The most appropriate indications and extent of resection of these neoplasms are discussed. The Authors report 4 cases of primitive adenocarcinoma of the duodenum treated by pancreaticoduodenectomy (2 cases), segmental resection (1 case) and palliative surgery (1 case) for the presence of omental and lymph-node metastases. Survival was 18 and 14 months in the patients who underwent pancreaticoduodenectomy and 9 months for the patient receiving palliative treatment; the patient who underwent segmental resection is still alive and healthy after 12 months. The Authors point out that adenocarcinoma of the duodenum is an uncommon neoplasm and stress the difficulty encountered in establishing an accurate diagnosis and appropriate surgical management. Better results can be obtained only with an early diagnosis. Chemotherapy and radiotherapy do not significantly improve survival.