A case of primary adenocarcinoma of the duodenum associated with Recklinghausen's disease and Caroli's disease provides the opportunity to review the literature. Malignant tumours of the duodenum are extremely rare and even rarer is their association with R's and Caroli's diseases. It should not be forgotten that in Recklinghausen's disease gastro-intestinal involvement is possible. Caroli's disease is diagnosed anatomopathologically. Surgical resection remains the sole satisfactory treatment when the tumour has not spread locally or at a distance. If it has, treatment must be palliative.