Endoscopic ultrasound has not yet become a routine procedure for the diagnosis and therapy planning of malignant lymphomas, and it was always restricted to patients with gastric or bowel involvement. From 1990 to 1992, 33 endoscopic ultrasound investigations have been performed in 25 patients with malignant lymphomas at the Cologne University Hospital. In addition, 21 of these patients had other (conventional) diagnostic procedures at the same time serving as reference. Endoscopic ultrasound showed lymphomas in 16/21 patients, and no evidence of lymphomas in 5/21 patients. The referencial investigations together showed lymphomas in 17/21 patients, and no evidence of lymphomas in 4/21 patients. Therefore, sensitivity was 94%. 5 of the patients in addition had involvement of the upper gastrointestinal tract's wall, proven by referencial investigations, which was diagnosed correctly in all cases. The pathological lymph nodes appeared mostly as echopoor, rather sharply demarcated and homogeneous. Their size was 7 mm to 55 mm in diameter, median 11 mm. The different histological types of lymphomas could not be distinguished by means of these criteria. Endoscopic ultrasound allows a detailed view at the mediastinal and epigastrical lymph node stations and may give important informations for the staging of malignant lymphomas.