Preoperative diagnosis of primary small intestinal neoplasms can be a challenge for both clinicians and radiologists. As a result of their infrequent occurrence, they invariably present difficult problems in diagnosis and management. These problems are reflected mainly in the delayed treatment and a very poor prognosis for such malignant tumours. Their morphological changes, however, shown in enteroclysis and CT, correlate almost perfectly with the lesions identified in the gross pathological specimens. This ability to accurately image a small intestinal neoplasm, independently of its size, anatomical localization and growing tendency, represents a major improvement in the diagnosis and management of these neoplasms. This paper, based on a large series of patients with primary small intestinal neoplasms, focuses on the recognition of their detailed radiological appearances when evaluated by enteroclysis and CT.