Prophylactic mastectomy generally occurs in two different patient populations: (1) high-risk women without breast cancer who undergo bilateral prophylactic mastectomy (BPM) to reduce their risk of developing breast cancer and (2) women with unilateral breast cancer who choose contralateral prophylactic mastectomy (CPM) to prevent cancer in the contralateral breast. The purpose of this article is to review the indications, outcomes, and trends in the use of BPM and CPM. J. Surg. Oncol. 2015 111:91–95. © 2014 Wiley Periodicals, Inc.