OBJECTIVE: To explore the risk factors of fat necrosis in pectoralis major myocutaneous flaps. METHODS: From May 1998 to December 2005, 82 patients underwent reconstruction of oral and maxillofacial defects with pectoralis major myocutaneous flaps in our hospital. Postoperative fat necrosis of the flaps was occurred in 10 cases. Logistic regression analysis was used to investigate the risk factors. RESULTS: (1) Logistic univariate regression analysis indicated that there was a significant correlation between fat necrosis of pectoralis major myocutaneous flap and the following risk facoars: obesity, subcutaneous tissues dissection performed by electrotome, the design of skin island beyond the seventh costal cartilage and smoking. (2) Logistic multivariate regression analysis suggested that there was a significant correlation between fat necrosis of pectoralis major myocutaneous flap and obesity, subcutaneous tissues dissection performed by electrotome, the design of skin island beyond the seventh costal cartilage, whereas there was no significant correlation between fat necrosis of flap and smoking. CONCLUSIONS: Obesity, subcutaneous tissues dissection performed by electrotome and the design of skin island beyond the seventh costal cartilage were the risk factors of fat necrosis in pectoralis major myocutaneous flap.link_to_subscribed_fulltex