Background Leptin has been associated with progression and poor survival in BC. Moreover, it is still controversial as to whether the effect of leptin depends only on its correlation with body mass index (BMI), or could be a direct role of adipokine in the development of BC. The aim of this study was to identify if there was a difference between serum leptin levels and insulin in obese patients with and without BC. Patients and Methods A cross-sectional study was made in 156 women, a group of 78 with obesity and BC and 78 with obesity without BC. When subjects agreed to participate, written informed consent was obtained from all subjects. Biochemical variables such as glucose, triglycerides, high-density and low-density lipoprotein, cholesterol, insulin, and leptin were measured and homeostasis model assessment (HOMA-IR) was calculated. Results The age, number of parities, glucose, HOMA-IR, and leptin were significantly different at P <.05. Conclusion Serum leptin levels and leptin/BMI ratio were statistically significantly increased in patients with BC. © 2013 Elsevier Inc. All rights reserved.