Conclusion: Upper airway surgery is associated with salutary effects on the blood coagulation characteristics of OSA patients, a benefit that may be protective against cardiac and cerebrovascular morbidity and mortality. Objective: Increased blood coagulation is an important factor linking OSA and cardiovascular complications. Surgery is an important method to treat OSA, but the effect of surgery on blood coagulation in OSA patients is unknown. Methods: the authors performed a prospective clinical trial of adult OSA patients who underwent surgery from 2012-2014. Preoperative and post-operative blood coagulation parameters and polysomnography (PSG) results were compared. Result: There were 61 subjects. The total rate of success in curing OSA was 11.5%. The rate of response after surgery was 40.8%. Overall, the Apnea-Hypopnea Index (AHI) improved after surgery (from 39.8 3 +/- 24.49 to 25.9 7 +/- 18.53, p<0.01). After surgery, serum platelet counts (PLT) decreased (from 242.5 +/- 52.6 to 230.9 +/- 40.7, p = 0.01), and Fibrinogen (FIB) levels declined (from 262.5 +/- 52.5 to 247.3 +/- 44.4, p = 0.02). Other blood coagulation parameters also improved: prothrombin time (PT) (from 10.6 2 +/- 0.62 to 10.8 6 +/- 0.70, p = 0.01), activated partial thromboplastin time (APTT) (from 26.9 8 +/- 4.94 to 27.7 8 +/- 3.02, p = 0.06), and Thrombin time (TT) (from 19.53 +/- 0.84 to 20.1 1 +/- 1.31, p<0.01).