The scope of this article is to evaluate the nutritional status, body composition and tumor characteristics of 31 patients with breast cancer attended at the Mastology Service of Hospital das Clínicas of the Federal University of Minas Gerais. Dietary data were obtained from the 24-hour dietary recall in the pre-operative state and analyzed by the DietWin Professional 2008 Nutrition Software. Body composition was assessed by bioelectrical impedance analysis. The tumor characterization data were collected from medical records. The mean age of patients was 50.75 ± 14.34 years. Excess body weight was found in 58% and waist circumference greater than 80 cm in 64.5% of patients Excessive consumption of oils and sugars was observed in 90.3% and 83.8%, respectively. Most had low intakes of calcium and vitamins B6, B12 and A. The predominant diagnosis was type II histological grade invasive ductal carcinoma in stage II or III. The prevalence of overweight and inadequate dietary intake demonstrate the need for individualized nutritional guidance and monitoring to improve the prognosis and quality of the life of patients.