OBJECTIVES: Breast cancer affects younger women in developing countries than in developed countries. In Malaysia, 50% breast cancer cases were diagnosed <age 50; and 13.5% patients with a family history carry deleterious BRCA mutations. These patients could reduce their risk of ovarian or a second breast cancer by undergoing risk-reducing interventions. We estimated the cost effectiveness of BRCA mutation testing in early-stage breast cancer patients with family history as defined by clinical practice guidelines. METHODS:   We developed a probabilistic decision analytic model to compare the projected lifetime costs and quality-adjusted life years (QALYs) accrued through BRCA mutation testing or routine clinical surveillance for a hypothetical cohort of 1000 early-stage breast cancer patients aged 40 years old with breast cancer family history. In the model, patients with deleterious BRCA mutation would decide whether to accept genetic testing, and upon testing positive, whether to undertake risk-reducing mastectomy, oophorectomy, tamoxifen, combinations or neither. We populated the model with data from published literature and local hospital database. We calculated the incremental cost-effectiveness ratio (ICER) from the perspective of the healthcare system (price year 2014), discounting cost and outcomes at 3%. RESULTS: In the base case scenario, the testing strategy generated 10.43QALYs over the lifetime and cost MYR26,427, while routine clinical surveillance generated 10.04QALYs and cost MYR25,212. The ICER was MYR3,149. In the testing arm, patients accrued most QALYs if they were true negative (7.43QALY), followed by true negative patients who declined testing (1.62QALY) and true positive patients who underwent oophorectomy (0.47QALY). ICER remained below MYR20,000 threshold over a wide range of testing acceptance rate (1-100%), because both incremental costs and QALYs gained changed in similar proportion. CONCLUSIONS: Our results suggested that offering BRCA mutation testing to early-stage breast cancer patients with family history may be cost effective in Malaysia compared to routine clinical surveillance.