Clinically, adenomyosis is usually seen in women in their thirties but has been seen from the early twenties into the postmenopausal period. Pathologically, adenomyosis is confirmed if there are ectopic endometrial glands and stroma in the myometrium. This induces hyperplasia and hypertrophy of the adjacent smooth muscle, causing uterine enlargement. The sonographic diagnosis of fibroids has long been confused with that of adenomyosis. Leiomyomata or fibroids are common in women, with an increased incidence of 7 times in blacks and nulliparous women. In adenomyosis, the myometrium has areas of increased echogenicity that may be subtle and best appreciated with higher-resolution ultrasound scanners. The diagnosis of adenomyosis should not depend only on the sonographic appearance but must rather consider the whole picture or triad of history, sonographic features, and signs of tenderness. Adenomyosis has been suspected as cause of infertility. The treatment of adenomyosis is mainly symptomatic.