Purposes of the study To evaluate the benefit of stenting the iliac vein in patients with residual iliac vein stenosis treated with catheter-directed thrombolysis for acute iliofemoral deep venous thrombosis. Procedures In this randomized prospective study, patients with a first-time acute lower extremity deep venous thrombosis that had persisted <14 days were treated with catheter-directed thrombolysis. After catheter-directed thrombolysis, patients with >50% residual iliac vein stenosis were randomly divided into two groups: catheter-directed thrombolysis + Stent Group and catheter-directed thrombolysis Alone Group. Patients received urokinase thrombolysis and low-molecular-weight heparin/oral warfarin during the hospitalization period and were administrated oral warfarin after discharge. Cumulative deep vein patency, the Clinical Etiology Anatomic Pathophysiologic classification system, the Venous Clinical Severity Score and the Chronic Venous Insufficiency Questionnaire score were evaluated. Findings The cumulative deep vein patency rate was 74.07% in the catheter-directed thrombolysis + Stent Group and 46.59% in the catheter-directed thrombolysis Alone Group. The mean postoperative Clinical Etiology Anatomic Pathophysiologic classification and Venous Clinical Severity Score was significantly lower in the catheter-directed thrombolysis + Stent Group than in the catheter-directed thrombolysis Alone Group. The mean postoperative Chronic Venous Insufficiency Questionnaire score was significantly higher in the catheter-directed thrombolysis + Stent Group than the catheter-directed thrombolysis Alone Group. Conclusions Placement of an iliac vein stent in patients with residual iliac vein stenosis after catheter-directed thrombolysis for acute lower extremity deep venous thrombosis increases iliac vein patency and improves clinical symptoms and health-related quality of life at mid-term follow-up compared to patients treated with catheter-directed thrombolysis alone.