Study Design. A prospective study of 313 patients who underwent major spinal surgery. Objectives. To determine the incidence of deep vein thrombosis after major spinal surgery in an east Asian population without antithrombotic prophylaxis. Summary of Background Data. Spinal surgery has been associated with few thrombotic complications (214%) compared with other reconstructive surgeries (2070%). It has also been well documented that the incidence of deep vein thrombosis in east Asians (10%) is lower than in westerners (20-70%) in total joint replacements. There has been no previous report on the incidence of deep vein thrombosis after reconstructive spinal surgery in east Asians. Methods. Three hundred thirteen patients who underwent major spinal surgery were evaluated prospectively. All patients were examined with duplex ultrasonography assessments of both lower extremities. No specific antithrombotic prophylaxes were used in any patients before or after surgery. Results. There were four patients with positive findings of deep vein thrombosis on duplex ultrasonography, and there was only one with clinically symptomatic deep vein thrombosis. The overall incidence of thrombotic complications was 1.3%, and the incidence of symptomatic deep vein thrombosis was 0.3%. Conclusion. Considering the low rate of deep vein thrombosis, routine screening and prophylaxis for deep vein thrombosis appears unwarranted in east Asians before or after major spinal surgery.