Although the claim has been made that there are early descriptions of what today we call endometriosis and adenomyosis in theses presented in Europe in the late 17(th) and during the 18(th) centuries, the first description of the condition initially named 'adenomyoma' is that provided in 1860 by the German pathologist Carl von Rokitansky, who found endometrial glands in the myometrium and designated this finding as 'cystosarcoma adenoids uterinum'. Over the following 50 years 'adenomyoma' (and endometriosis) were considered pathologies separate from the so-called 'haemorrhagic ovarian cysts', and it was not until 1921 that this condition was recognized to be of endometriotic origin. The first systematic description of what is today known as adenomyosis was the work of Thomas Stephen Cullen who, at the turn of the 19(th) century, fully researched the 'mucosal invasion' already observed by a number of investigators in several parts of the lower abdominal cavity. Cullen clearly identified the epithelial tissue invasion as being made of 'uterine mucosa' and defined the mechanism through which the mucosa invades the underlying tissue. In 1925, 2 years before Sampson created the term 'endometriosis', Frankl created a name for the mucosal invasion of the myometrium and clearly described its anatomical picture; he called it 'adenomyosis uteri' and explained that 'I have chosen the name of adenomyosis, which does not suggest any inflammatory genesis as do terms like adenometritis, adenomyositis, adenomyometritis, still employed'. The current definition of adenomyosis was finally provided in 1972 by Bird who stated: 'Adenomyosis may be defined as the benign invasion of endometrium into the myometrium, producing a diffusely enlarged uterus which microscopically exhibits ectopic non-neoplastic, endometrial glands and stroma surrounded by the hypertrophic and hyperplastic myometrium'.