Methods for treating FSH related conditions, such as prostatic intraepithelial neoplasia, pedophilia, infertility, or vaginal bleeding, with GnRH antagonists are disclosed. The methods of the invention generally feature administering to a subject a GnRH antagonist suitable for in vivo administration and able to reduce both plasma FSH and LH levels in a subject, in an amount or in a formulation effective to reduce plasma FSH levels in the subject to a symptom alleviating level. In vitro fertilization and male contraceptive methods are also provided.