This text describes double contrast techniques for the diagnosis of most diseases affecting the upper gastrointestinal tract, small bowel and colon. The text illustrates the principles of examination, describes how to perform the techniques in each area of the GI tract and interprets the radiographs. Radiographs demonstrate normal anatomy and the spectrum of pathologic changes to assist in accurate diagnosis, and radiographic demonstration of subtle abnormalities of the mucosal surface aims to help readers diagnose inflammatory and neoplastic lesions. An emphasis on endoscopic correlation of radiographic findings describes the interrelationship between radiology and endoscopy throughout the GI tract, pointing out areas where radiology provides superior diagnostic data - and where endoscopy offers advantages.