ABSTRACT
Tibolone (Livial, NV Organon, Oss, Netherlands) is a synthetic steroid which exhibits estrogenic, progestogenic and androgenic activity. In the endometrium, tibolone dose not have estrogenic activity, but dose have intrinsic progestogenic activity. Therefore, it dose not stimulate the endometrial tissue which usually undergoes atrophy. Tibolone has been associated with a relatively low incidence of vaginal bleeding and endometrial hyperplasia. Recently. a few reports have been published even less frequently describing invasive endometrial cancer during tibolone therapy. We report a case of histologically diagnosed adenocarcinoma of the endometrium in women using tibolone. Although we do not suggest causability between the use of tibolone and the development of endometrial malignancy, but we should alert physicians to thorough investigation in patients presenting with vaginal bleeding and the increase of endometrial thickness by sonogram while on tibolone.