PURPOSE: In western countries, the reported incidence of deep vein thrombosis (DVT) after total hip arthroplasty (THA) ranges from 12 to 23% when an accepted form of prophylaxis is used but when it is not, it ranges from 48 to 70%. However, the incidence of postoperative DVT in Asia has always been considerably lower (20~30%) and compare to western countries and no clear indication for prophylaxis has been suggested. The aim of this study was to document the incidence of DVT among Koreans, and to find the correlation between DVT and its risk factors after total hip arthroplasty. METHOD: 196 patients, who underwent THA from 2002 to 2004, were evaluated to figure out the incidence of DVT and its correlation with well known risk factors, such as age, body mass index (BMI), gender, preoperative coagulation assays (platelet, PT and aPTT) and operation time. All patients wore elastic compression stockings, and early ambulation was encouraged. Venography or Doppler sonography was obtained routinely between 7th and 10th postoperative days. RESULT: The incidence of DVT and pulmonary embolism following THA was 12.6% (25 cases) and 0.5% (1 case), respectively. The mean age of the patients evaluated was 49. 12 cases showed thrombi in the muscle branch below the knee, 9 cases in the posterior tibial vein and 4 cases in the veins above the knee. Age and aPTT were statistically significant with a higher incidence of DVT (P<0.05). However, no correlation between DVT and other factors, such as PT, platelet count, transfusion rate, operation time and BMI, was identified. CONCLUSION: The incidence of DVT in our study was 12.6%. Age and the preoperative aPTT level were significantly associated with the development of DVT after THA.