This study aimed to determine the effects of demographic, clinical, and therapeutic variables in development of seromas. The relation between development of seromas and age, preference for surgery, tumor size, existence of axillary lymph nodes and lymph nodal metastases, number of lymph nodes removed, type of surgical equipments used, drainage duration, drainage flow rate, and whether or not neoadjuvant chemotherapy was received; dead volume was reduced; or pressure garment was used in patients who received surgery due to breast cancer between 2000 and 2005 years. Mean age of 119 patients included in the study was 53.13+/-13.26 (range 26-79). Seromas were observed in 17 (14.28%) patients. In multivariate logistic regression analysis an association of postoperative seroma formation was noted with a drainage flow rate greater than 50 mL/day after 48th hours following breast surgery (p=0.007), while other variables investigated herein are not associated with development of seromas. We conclude that a drainage flow rate greater than 50 mL/day after 48th hours is a predicting factor for seroma formation in breast cancer patients. Thus, we do not recommend terminating the drainage before flow rate at 48 hours is seen and daily drainage is lower than acceptable limit.