Endometriosis and adenomyosis are two frequent diseases that impair women's quality of life by causing pain and infertility. Both endometriosis and adenomyosis are heterogeneous diseases that manifest as different forms. Adenomyosis may be described as diffuse adenomyosis, focal adenomyosis especially of the outer myometrium and cystic adenomyoma. Endometriosis has three phenotypes: superficial peritoneal endometriosis (SUP), ovarian endometrioma (OMA), and deep infiltrating endometriosis (DIE). These two diseases are closely linked, and it is now clear that adenomyosis can either arise on its own or coexist with endometriosis. There is a strong clinical relationship between endometriosis and adenomyosis according to their respective phenotypes. Various classifications are available to describe both diseases. Transvaginal ultrasonography (TVUS) and/or pelvic magnetic resonance imaging (MRI) are the first examination performed when endometriosis or adenomyosis are suspected. These two imaging techniques, used in a combination manner, allow accurate description of both endometriosis and adenomyosis, to assess the diagnosis and to improve clinical and surgical care. In this review, we described the different imaging aspects of endometriosis and adenomyosis to help the less experienced radiologist or gynecologist in the diagnosis and evaluation of those diseases.