AIMS AND BACKGROUND: Old age is associated with comorbidity and decreased functioning which influences treatment decisions in elderly breast cancer patients. The purpose of this study was to identify risk factors for complications after breast cancer surgery in elderly patients, and to assess mortality in patients with postoperative complications. METHODS: We retrospectively considered all female patients aged 65 years and older with invasive and in situ breast cancer who were diagnosed and treated between 1997 and 2012 in the Department of General and Geriatric Surgery of the University of Naples "Federico II". RESULTS AND CONCLUSION: 449 patients received surgery, of whom 18,2% (n = 82) developed one or more postoperative complications. The odds ratio of having postoperative complications show an increase with age, reaching statistical significance only for patients older than 85 [OR 5,75 (95% confidence interval 2,38-14,04); p < 0,001]. Number of concomitant diseases [OR 2,51 (95% CI 1,17 - 5,45); p = 0,01 for 3 or more concomitant diseases] and polypharmacy [OR 16,7 (95% CI 9,12 - 30,58); p < 0,0001) are associated to an increased risk of postoperative complications. Overall survival was worse in patients with postoperative complications [HR 2,06 (95% CI 1,52-2,70), p < 0,001]. This increased risk of mortality is probably due to geriatric parameters such as comorbidity or poor physical function, more than to higher complication rates