Objective: Gonadotrophin-releasing hormone agonist (GnRHa) has been commonly used for the medical treatment of prostate cancer, precocious puberty, endometriosis, adenomyosis and uterine leiomyomas. GnRHa therapy in cases of symptomatic uterine leiomyomas aims for the reduction of their size and remission of symptoms such as menometrorrhagia, causing a state of hypoestrogenemia. This is considered to be a helpful preoperative strategy in cases of large myomas, or anemia because of abnormal vaginal bleeding. The aim of this retrospective study was to examine the clinicopathological changes in uterine leiomyomas exposed to preoperative GnRHa therapy for two up to six months. Materials and Methods: The study group consisted of 10 premenopausal patients who were treated with GnRHa prior to surgery. Results: In all cases the size of leiomyomas was reduced after GnRHa therapy. A microscopic review of the surgical specimens showed increased cellularity and ischemic type of necrosis. Conclusion: Morphological changes of uterine leiomyomas are often associated with preoperative GnRH agonist therapy. The differential diagnosis from uterine leiomyosarcomas includes absence of mitotic activity.