The new series A-Z Notes in Radiological Practice and Reporting provides practical guides for residents and general radiologists, organized alphabetically, primarily according to disease or condition. All booklets are designed so as to cover a large spectrum of topics referring to different anatomical regions of interest. Entries typically include a short description of pathological and clinical characteristics, guidance on selection of the most appropriate imaging technique, a schematic review of potential diagnostic clues, and useful tips and tricks. The present booklet, enriched by illustrations and schemes, is devoted to gastrointestinal imaging. Major topics in CT and MR imaging of the small bowel, colon, rectum, and anus are treated concisely in alphabetical order. For each topic a brief review of clinical features and pathology is presented, followed by a short description of imaging technique and an accurate review of imaging findings and signs which are useful in the differential diagnosis of gastrointestinal disease.