BACKGROUND Deep venous thrombosis (DVT) is a disease associated with high morbidity in 40-60% patients who underwent Total Knee Arthroplasty (TKA). Postthrombotic syndrome (PTS) is a common long-term complication that may develop within 6 months or more than 2 years after episode of DVT. OBJECTIVE To examine the prevalence of PTS in patients who had history of previous DVT and non-previous DVT at least 2-year follow-up period after TKA. METHODS Retrospective chart review was done. All patients who underwent TKA during October 2002-2005 were included. They were postoperatively assessed for PTS with Villalta score and duplex ultrasonography at > or =2 years. The confirmed diagnosis of DVT was done by contrast venography. RESULTS 22 of 76 patients (56 previous DVT 20 non-previous DVT) had PTS based on the clinical assessment. The previous-DVT group had significantly higher risk to PTS (OR = 1.59; 95% CI: 1.294-1.949; p-value = 0.001). When diagnosed with duplex ultrasonography, 36 in 56 patients of previous-DVT group and 8 in 20 of non-previous-DVT group were found positive venous reflux. Most of venous reflux occurred at popliteal vein (77%) and posterior tibial vein (59%). CONCLUSIONS After TKA, the patients who developed DVT had higher risk to PTS (OR = 1.588). Treatment of DVT may not decrease this risk. Prevention of DVT becomes an important approach to prevent PTS.