215 women with breast cancer were evaluated for fertility preservation before chemotherapy. Of those, 79 elected to undergo controlled ovarian stimulation (COH) with letrozole and gonadotropins for embryo or oocyte cryopreservation. The 136 patients who declined served as controls.There were no significant differences between the study and control groups regarding age at diagnosis, breast cancer prognostic parameters (tumor size, grade, number of positive lymph nodes, estrogen receptor status, her2-neu overexpression and vascular space invasion), and chemotherapy regimens. There was no difference between the two groups in the projected 10 year relapse, breast cancer specific mortality or overall mortality. There were 3 recurrences or contralateral breast cancers (2 distant, 1 locoregional) in the letrozole group, and 11 in the control group (9 distant, 1 locoregional, 1 contralateral breast).