Seroma formation is a known complication after any surgery where excessive dissection of subcutaneous tissue leads to disruption of lymphatic channels. Seroma formation, its sequelae and frequent visits to doctor for their management are a common source of discomfort for patients. Objectives: Comparison of frequency of seroma formation after flap fixation versus convetional closure after modified radical mastectomy. Study Design: Randomized control trial. Setting: Department of Surgery, Allied Hospital Faisalabad. Period: 6 months from May 1, 2016 to October 31, 2016. Material & Methods: After permission from Hospital ethics committee and informed consent from patients, 70 patients were randomly divided into two groups (35 participants in each group). Findings were noted and data was analyzed statistically. Results: It was observed that incidence of seroma formation following modified radical mastectomy was lower with flap fixation technique (14.29%) as compared to conventional closure of wound margins (42.86%). Conclusion: Flap fixation technique is better approach compared to conventional method to prevent seroma formation.