According to the World Health Organization (WHO), 34.7% of females in the United States are obese (BMI ≥ 30) in 2014, compared to 32.5% in 2010. The previous research has demonstrated high BMI as an independent risk factor for surgical complications after breast surgery. As more patients become obese, we sought to examine whether increasing obesity had an effect on outcomes of women who underwent a unilateral mastectomy without breast reconstruction.