Conventional ultrasonography is widely used as a diagnostic investigation in gastroenterology. Ultrasonically visible 'target or halo sign' caused by lesions in the upper GI-tract has no specificity or biological significance, so conventional ultrasonography cannot be used as an adequate investigation for detecting lesions in the upper GI-tract. Recently endoscopic ultrasonography was developed with the aim of improving the diagnostic potentialities of ultrasonography. Using an ultrasonic device it is now possible not only to detect lesions in the upper GI-tract, but also to assess the exact extent and depth of both local infiltration and adjacent metastases. Rapid differentiation between intramural and extraluminal lesions can readily be accomplished. The superiority of this new technique in the diagnosis of tumours of the papilla of Vater, and in particular in establishing preoperative tumour staging, has been demonstrated in comparison with other imaging techniques. These preliminary results in a small number of patients must be confirmed by further studies involving clinical trials with a large number of patients.