Women who inherit a mutated copy of the BRCA gene have a higher lifetime risk of developing breast cancer. No large epidemiological studies exist looking at BRCA mutation carriers in UK populations. All patients with BRCA1/BRCA2 mutation identified between 1995 and 2015 were included. Individuals were identified from a prospectively gathered data base. Genetics case-notes were obtained and retrospective analysis performed. 581 female BRCA mutation carriers were identified with a median age of 34 (18-81) at the time of testing. Of the 301 women who underwent diagnostic testing (symptomatic) 246 had been diagnosed with breast cancer, 89 with ovarian cancer and 37 had both at time of testing. Median age at diagnostic test was 51 (25-81). 33% of women underwent risk-reducing mastectomies (RRM); median age at surgery 45. This compares with 37% of women in this diagnostic group who underwent Risk-reducing bilateral salpingo-oopherectomies (RRBSO) at a median age of 46. Two hundred and eighty women underwent predictive testing (family history, asymptomatic), median age 36 (18-81). 34% of women in this predictive group underwent RRM, median age 37. There was a 29% uptake of RRBSO (median age 44 years). Fifteen women (5%) developed breast cancer after being tested; none of these had undergone RRS. This unique study of all BRCA mutation carriers in Wales shows considerable variation in uptake of RRS. The decision to undergo RRS is complex and involves a number of factors, including a woman's age and life stage. As BRCA testing becomes more frequent and more gene mutation carriers are identified there will be significant implications for service allocation, screening demands, and provision of risk-reducing surgery for this high-risk patient group.