Background: Prior estimates of costs associated with CPM have been limited to single institution studies or simulation-based decision models and have failed to take into account costs associated with breast reconstruction (BR), also correlated with CPM. Our study uses actual charges incurred in a population-based dataset to estimate costs for the initial procedures as well as surgical complications and additional (addl) breast procedures for CPM and UM. Methods: Women receiving immediate CPM or UM in 2008-2010 were identified from SPARCS, the state of New York’s all payer data reporting system for inpatient stays and outpatient encounters. Claims submitted within two years of the primary breast surgery were collected. Surgical complications and addl breast procedures were also identified. Summed charges were transformed to costs following published cost-to-charge ratios. Log-linear models were fitted to estimate costs of CPM and UM, controlling for age, race, year, insurance status, BR, and the interaction between extent of mastectomy and BR. Results: In our final cohort of 13,110 women, 11% received CPM. Median total costs were 46% ($7,521.72) higher for CPM than UM (p < .01). Those with CPM were more likely than UM to experience complications (30% v 21%, p < .01) and have addl breast procedures (80% v 45%, p < .01), and thus higher follow up costs. However, BR was not uniformly distributed by extent of surgery, as 93% of CPM and 46% of UM patients received BR (p < .01). When stratified by BR, rates of complications did not differ by CPM or UM, but were much higher for those who underwent BR than those who did not (31% and 12% respectively, p < .01). Controlling for BR and patient characteristics, costs were similar between CPM and UM in terms of complications (p = .27), addl breast procedures (p = .19), and overall follow up (p = .98). Conclusions: Despite lack of survival benefit, a growing number of average-risk women elect CPM, often with BR. In our cohort, the complications, addl breast procedures, and higher follow up costs associated with CPM were driven by BR. These additional costs associated with BR should be considered when evaluating the benefit-cost ratio of CPM.