OBJECTIVE To investigate the efficacy and safety of venous thrombus embolism (VTE) prophylaxis according to risk stratifications after spinal surgery. METHODS From June 2008 to June 2009, we separated 298 spinal patients who had different VTE risk factors into low-, medium- and high-risk groups for 22 cases, 48 cases and 228 cases respectively. Physical prevention measures such as thigh-length thromboembolic deterrent stockings (TEDS) and pneumatic sequential compression device (PSCD) were used in low- and medium-risk groups. In high-risk groups, low molecular weight heparin(LMWH) was applied in addition to physical prevention measures. Lower limb vascular doppler ultrasonography was used to monitor thrombosis pre- and postoperatively. Simultaneously the occurrences of epidural or wound hematoma, mucosal bleeding, thrombocytopenia caused by low molecular heparin and nerve damage caused by extradural hemorrhage were monitored. RESULTS Among the 298 cases of patients with spinal surgery, DVT occurred in 23 cases, the incidence of DVT was 7.7%. There were 0, 2 and 21 patients with positive findings of deep vein thrombosis on duplex ultrasonograph respectively in low-, medium- and high-risk groups. There was no case of PE. All DVT was thrombosis in calf which was distal to the knee. There was no clinical symptom of VTE. The DVT needed no therapy. The vein with thrombosis was recanalized 3 months after operation. No case caught epidural or wound hematoma, mucosal bleeding, thrombocytopenia caused by low molecular heparin or nerve damage caused by extradural hemorrhage. CONCLUSIONS Individual VTE prophylaxis was taken according to risk stratifications. No VTE of clinical value or no complications from prophylaxis happened. So our prophylaxis is effective and safe. But more prospective, case-control studies are needed to assess the efficacy and safety of VTE prophylaxis.