Degarelix (INN) or degarelix acetate (USAN) (tradename: Firmagon) is a hormonal therapy approved for the treatment of prostate cancer. Since testosterone, a male hormone, promotes the growth of many prostate tumors, reduction of circulating testosterone to very low (castration) levels is often the treatment goal in the management of advanced prostate cancer. Degarelix, an antagonist of GnRH, has immediate onset of action through binding to GnRH receptors in the pituitary gland and blocking their interaction with GnRH. The result is a fast and profound reduction in LH, FSH and in turn, testosterone suppression. Its activity in suppressing the ovaries of premenopausal women might therefore be faster than other GnRH analogues, possibly by several weeks. The probable difference in onset of action could have significant clinical value for patients who are candidates for short-term neoadjuvant endocrine treatment.