Deep gastrointestinal involvement in endometriosis is characterised by fibrous, retractile thickening of the intestinal wall. The most common location is the upper rectum, in contiguity with a lesion of the torus uterinus. As part of a preoperative assessment, it is essential to establish an accurate and exhaustive map of intestinal lesions so that the surgeon can plan his actions. Transvaginal sonography and MRI correctly analyse pelvic and rectal involvement. Given the frequency of multiple intestinal sites, particularly sigmoid and associated ileo-caecal lesions, water enema CT should be performed. The role of rectal endoscopic sonography is debated.