Purpose: Seroma formation is still major complication of abdominal donor site after TRAM flap surgery in spite of various efforts to reduce seroma formation such as closed suction drain. We performed a clinical study, that quilting suture at abdominal donor site can prevent seroma formation. Methods: Between May 2002 and September 2008, we performed 600 breast reconstructions using a unilateral TRAM flap except patients who has smoking history or abdominal scar. We performed 300 breast reconstructions without quilting sutures (A: Experimental group) until January 06, and after then 300 reconstructions with quilting sutures (B: Control group). We compared total drain output (mL), time to drain removal (days), and donor site complications between two groups. Results: There were no statistical difference at BMI (p=0.28) and time to remove suction drain between two group. (A: 8.37, B: 9.69) (p=0.40) But, total drain output was reduced with quilting suture. (A: 432.5, B: 495.2) (p=0.005) And also complication rate was decreased, such as seroma formation, epigastric bulging. (A: 1%, B: 7%) (p=0.005) Conclusion: Quilting suture is a simple and reliable method to reduce seroma formation and abdominal donor site complication.