The introduction of endosonographically guided fine-needle biopsy has led to increasing use of longitudinal scans in the endosonographic diagnosis of tumors and other diseases of the upper gastrointestinal tract as well as of the pancreas. In this handbook, experts concentrate primarily on practical aspects of using endosonography with longitudinal scans. Examination techniques, interpretation of the ultrasound images, and normal anatomy with important guiding structures are demonstrated by means of 3D CT images and the corresponding endosonographic images. In addition, pathological endosonographic findings and the current status of diagnosis using fine-needle biopsy are described.