Endometriosis is a common gynecological condition affecting up to 15% of the general female population. Here, we present a systematic review of imaging techniques of endometriosis. The aim of this review is to determine the most accurate site-specific preoperative diagnostic tools in order to map, locate, evaluate the extension, and stage the disease. There are important reasons to stage endometriosis: to create a common language, to enable specificity of diagnosis, standardize comparisons, and to facilitate research applications. The requirements of an ideal endometriosis classification system are that it be empirically and scientifically based, be of general consensus, have unambiguous definition of terms, be comprehensive in all cases, have a simple translation from anatomic features to verbal description, reflect disease, predict fertility, predict pain relief, be useful to guide treatment, indicate risk of recurrence, identify clinical situations in which it does not apply, be simple to calculate, and be easy to communicate to women. An extensive search of papers regarding imaging techniques in endometriosis was performed in Pubmed from January 1992 to February 2018, including original peer-reviewed papers, reviews, and international guidelines.