In 19 patients with gastrointestinal tumors the diagnosis was made by ultrasound. 7 patients were examined for further investigation of an abdominal mass; 12 patients, presented with symptoms suggesting malignants, e. g. weight loss, vomiting, fever, abdominal pain, and/or anaemia from bloodloss were first investigated by ultrasound. In 5 patients with colon tumors, diagnosed by ultrasound, a resection and anastomosis was possible. 13 cases were found to be inoperable during laparotomy, one patient had an ileocolitis Crohn with stenosis. Ultrasonic examination with real-time scanning technique proved to be a valuable method as a screening procedure for patients with suspected gastrointestinal tumors. During the same procedure local (mesenteric) or liver metastases can be detected. A normal abdominal ultrasonography does not exclude malignant intestinal lesions in any location during the early stage and in the region of cardia and rectum even in the more advanced stage.