During the 3-year follow up period, 21 VTE patients (40%; including those died) were lost to follow up. Among patients receiving follow up, all were treated with warfarin for anti-coagulation. In addition, immunological examination and detection of D-Dimer were also carried at designed time points. Our results showed about 30% of VTE patients receiving follow up did not have increase of D-Dimer level any more at 0.1~1 year after warfarin discontinuation when the immunological examination and detection of D-D dimer showed normal.