Objective: Lymphedema is one of the most debilitating outcomes of breast cancer treatment. We aimed to compare the demographic and clinical characteristics of breast cancer patients with and without lymphedema, to assess risk factors for lymphedema, and to evaluate treatment outcomes in lymphedema patients. Materials and Methods: Demographic and clinical characteristics of 84 women with previous surgery for breast cancer who presented to the outpatient clinic between March 2014 and May 2015 were retrospectively extracted from patient records. Results: Upper extremity lymphedema was detected in 34 of 84 patients (40.5%). The mean age, body mass index, the number of positive lymph nodes and the number of patients with postoperative radiotherapy were significantly higher among patients with lymphedema than those without (p<0.05). Educational level of patients with lymphedema was significantly lower than the other group (p<0.05). The correlation analysis revealed an association between age, educational level, body mass index, tumor stage, number of positive lymph nodes, postoperative radiotherapy and presence of lymphedema. Postoperative radiotherapy was detected as the only independent risk factor by logistic regression analysis. Fourteen out of 26 lymphedema patients were assigned to education, skin care, exercise and compression bandaging therapy. Upper extremity volumes and volume differences were significantly improved after treatment. Conclusion: Advanced age, low educational level, obesity, tumor size, the number of positive lymph nodes and postoperative radiotherapy correlated with the development of lymphedema. Within these factors, postoperative radiotherapy was detected as an independent risk factor for the development of lymphedema. Patient education, skin care, exercise and compression bandage therapy are effective treatment options in breast cancer-related lymphedema.