An increasing trend towards later childbearing has been reported recently in many developed countries. Although the incidence of reproductive age in women who have delayed pregnancy with cancer is 10%, they may be concerned regarding the preservation of ovarian function due to advanced fertile age and with the impact of cancer treatment on later fertility. Among multiple strategies controlled, ovarian stimulation for embryo or oocyte cryopreservation is currently the most established method for fertility preservation. It is important to choose the appropriate ovulation induction protocol prior to oncologic treatment, because most of these patients have only the chance of a single cycle to conceive. Current treatment protocols offer a minimal time delay until oncologic treatment is commenced. In urgent settings, random-start ovarian stimulation represents a new technique which provides a significant advantage by decreasing the total time of the treatment, because it may be started irrespective of the phase of the cycle without compromising oocyte yield and maturity before cancer treatment. However, in patients with oestrogen-sensitive cancers stimulation, protocols using letrozole are currently preferred over tamoxifen regimens, and therefore, it may be highly advisable to use letrozole with gonadotrophins routinely as a safe, effective and novel protocol of ovulation induction.