DVT and pulmonary embolisms (clots in the lungs) are conditions known as venous thrombosis. Fortunately, venous thrombo embolisms are rare conditions, with about one in 2,000 people in the UK affected each year. DVT is less common in people under the age of 40 (less than one in 3,000) and more common in people over the age of 80 (up to one in 500).A DVT usually develops in the calf, but it sometimes also occurs in the thigh. Occasionally, other deep veins in the body are affected. Inflammation of surface veins (superficial phlebitis) is much less serious. Deep vein thrombosis (DVT) is common seen in patients undergoing spine surgery. However, its prevalence and associated risk factors have not been well understood yet. This retrospective case cohort study was designed to investigate risk factors for postoperative DVT using retrospectively collected data from department of spine surgery between 07/2013 and 07/2014. Univariate analysis and binary logistic regression analysis were used to determine risk factors for DVT. A total of 861 patients were admitted into DVT-associated analyses, including 410 males and 451 females, aged from 15 to 87 years old (median 54, IQR 18). Of them, 147 cases (17%) sustained postoperative DVT. Using prophylaxis for DVT is neither complicated nor expensive. In fact, several studies show that preventing this disease is cheaper than treating its consequences. Giving prophylaxis to those who are at risk should be a routine practice in the hospital. Basically, the approach to DVT prevention is similar to preventing postoperative wound infections. As with antibiotic administration, the keys to preventing DVT in know who is at risk, when to apply the preventive measure, and applying the appropriate measure.