Chocolate cysts and adenomyosis are both diseases caused by ectopic endometrium, with the same cause but different sites of onset and different symptoms. Chocolate cysts are a manifestation of endometriosis, caused by ectopic endometrium to the ovaries, while adenomyosis is the invasion of endometrial glands and mesenchyme into the myometrium. Chocolate cysts occur when the size of the cyst varies, single or multiple, mostly manifested as lower abdominal pain and dysmenorrhea, rupture of larger cysts can cause sudden severe pain, belonging to one of the acute abdominal syndrome. Adenomyosis is characterized by an enlarged uterus with a spherical shape, and the main clinical manifestations are increased menstrual flow and progressively worsening dysmenorrhea. In terms of treatment, medication is not effective, and laparoscopic surgery is the mainstay of treatment in cases of chocolate cysts. Women with adenomyosis who do not respond to medication and who have chronic severe dysmenorrhea and have no desire to have children can undergo hysterectomy.