PURPOSE: Total flap failure remains a reported complication, primarily due to arterial thrombosis. Although numerous studies have compared different intraoperative and postoperative anticoagulant regimens, none have specifically addressed the effectiveness of preoperative acetylsalicylic acid treatment. In this study, it was aimed to investigate the effect of pre-operative aspirin administration on free flap survival rate in lower extremity reconstruction. MATERIALS AND METHODS: This retrospective study included patients who underwent free flap transfers for lower extremity reconstruction. The patients were divided into two groups: those who received preoperative acetylsalicylic acid treatment and those who did not. The two groups were compared in terms of flap success and complication rates. RESULTS: A total of 117 patients were included. Of these, 42 patients received preoperative acetylsalicylic acid, while 75 did not. Trauma was the most common etiology, while burns were the least common. There was no statistically significant difference between the groups in terms of flap type or recipient artery (p >
0.05). Arterial thrombosis developed in 13 patients (11%), of whom only one had received preoperative acetylsalicylic acid. 7 of these patients experienced total flap loss. There was a statistically significant difference regarding total flap loss and arterial thrombosis (p <
0.05). CONCLUSION: Preoperative acetylsalicylic acid treatment may improve free flap success rates by preventing arterial thrombosis. It was found to be effective in preventing arterial thrombosis when initiated in the preoperative period, before endothelial damage occurs during anastomosis. However, Clinicians should weigh the potential benefits of reduced thrombotic events against the risks of complications, such as hematomas, when considering preoperative aspirin administration.