Background: Considerable attention has been paid to the problem of repeated breast-conserving surgery (BCS; i.e., lumpectomy), but the costs and complications due to these additional operations are not well-characterized. To address this issue, a retrospective review of insurance claims data for BCS patients was performed to assess complications and economic outcomes. Methods: Private claims from a single insurer were analyzed for 9,457 women undergoing BCS for breast carcinoma between January 2010 and September 2013 in either Illinois, New Mexico, Oklahoma, or Texas. Patients undergoing a second open breast surgery (i.e., mastectomy or BCS) within 90 days of the initial BCS were classified as having a repeated surgery. Complications were identified via a set of 8 CPT and 25 ICD9 diagnosis and procedure codes related to breast cancer treatment. The analysis included these complications and the total cost of all allowed healthcare claims within two years following diagnosis. Results: 7,287/9,457 patients (77% ±0.9%, 95% confidence interval) had one BCS operation and 2,170 patients (23% ±0.9%) had at least one repeated surgery (Table). The mean patient age was 53 years. The mean two-year cost for patients undergoing a single BCS was $88,733 (±$1,884) and the cost for patients undergoing a repeated breast surgery was $104,482 (±$3,719), $99,554 for a second BCS and $117,967 for subsequent mastectomy. The mean added cost due to a repeated surgery was $16,352. The percentage of patients experiencing at least one complication was 23.7% (±1.0) for those undergoing one BCS only and 35.2% (±2.0) for those undergoing a repeated surgery. Conclusions: For the 23% of women undergoing a second operation after BCS, complications were 49% more common and the mean total cost of surgery increased more than $16,000, demonstrating a patient-centered and fiscal imperative to reduce reoperations in BCS for breast cancer.