In 32 patients with benign or malignant disease of the pancreas direct ultrasound imaging of the pancreas was performed during the operative procedure. Benign could be distinguished from malignant lesions on the basis of different ultrasound patterns, changes in the pancreatic duct and size of the organ. A further improvement in diagnostic accuracy was obtained by intraoperative staging with ultrasound-directed small-needle biopsy of that part of the pancreas which looked suspicious macroscopically and by ultrasound. Previously unknown tumour infiltration was also revealed by ultrasound imaging. Intraoperative ultrasound is a new helpful method for the surgeon. Since it is easy it should be used in all doubtful instances, even though the interpretation requires considerable experience.