Adenomyosis is a common benign uterine pathology that is defined by the presence of islands of ectopic endometrial tissue within the myometrium. It is asymptomatic in one third of cases, but when there are clinical signs they remain non-specific. It can often be misdiagnosed on sonography as it may be taken to be multiple uterine leiomyomata or endometrial thickening, both of which have a different prognosis and treatment. Adenomyosis is often associated with hormone-dependent pelvic lesions (myoma, endometriosis, or endometrial hyperplasia). It is less commonly connected to infertility or obstetrical complications and indeed any direct relationship remains controversial. The purpose of imaging is to make the diagnosis, to determine the extent of spread (focal or diffuse, superficial or deep adenomyosis, adenomyoma), and to check whether there is any associated disease, in particular endometriosis. The aim of this article is to provide assistance in recognising adenomyosis on imaging and to identify the pathologies that are commonly associated with it in order to guide the therapeutic management of symptomatic patients. Pelvic ultrasonography is the first line investigation. Sonohysterography can assist with diagnosis in some cases (pseudothickening of the endometrium seen on sonography). MRI may be used in addition to sonography to back up the diagnosis and to look for any associated disease.