To report an unanticipated pregnancy during ovarian ablation treatment with goserelin (10.8 mg SC every 12 weeks) in a 26-year old female with breast cancer. Review of the current literature and reports in MEDLINE, PubMED, and EMBASE using searches with keywords "goserelin, pregnancy, breast cancer, breast neoplasms, fertility, ovarian ablation, gonadotropin releasing hormone agonists/analogs, leuprolide, pregnancy complications, teratogens" (July-September 2010). Only 3 other reports of failures with goserelin administration at ablative doses in breast cancer patients were discovered. For physicians and breast cancer patients using a GnRH analog, it is important to be aware of the possibility of inadequate ovarian function suppression and the potential for pregnancy.