OBJECTIVES: Because of the looming obesity epidemic in the US, we aimed to compare the utilization pattern of breast reconstruction between obese and non-obese patients and assess the association between obesity and postoperative complications as well as healthcare costs.  METHODS: Using MarketScan Health Risk Assessment and MarketScan Commercial Claims & Encounters databases, we identified breast cancer patients who underwent mastectomy between 2009 and 2012. We categorized patients’ obesity status based on the World Health Organization classification system: non-obese, obese class I, and obese class II\III. Temporal trends in breast reconstruction were assessed using the Cochran-Armitage trend test. Multivariable logistic regression models were performed to determine the association between obesity and the occurrence of postoperative complications. Healthcare costs were compared using a generalized linear model.  RESULTS: Among 2,558 patients treated with mastectomy, the breast reconstruction rate of non-obese patients (76.2%) was significantly higher than patients in obese class I and class II&III (63.3% and 60.2%, respectively; P<.001). Compared with non-obese patients, obese patients had significantly higher rates of infection (odds ratio [OR], 1.53, for obese class I, and OR, 1.60, for obese class II&III, both P <0.01), wound (OR, 1.51, P = .01 for obese class I, and OR, 1.98, P < 0.001 for obese class II&III), and perfusion complications (OR, 1.73, P = .01 for obese class I, and OR, 2.21, P < .01 for obese class II&III). The mean postoperative complication cost for non-obese patients ($4,684) was significantly lower than those for obese class I patients ($6,250) and obese class II&III patients ($7,868; P <.001).  CONCLUSIONS: Our analysis documented a significant gap in breast reconstruction between obese and non-obese patients. Further clinical research is needed to identify ways to reduce the risk of complications among obese patients and thus reduce this disparity.