Background:Catheter-directed thrombolysis (CDT) has been a mainstay in treating deep venous thrombosis (DVT).However,the optimal dosage of a thrombolytic agent is still controversial.The goal of this study was to evaluate the safety and efficacy of low dosage urokinase with CDT for DVT.Methods:A retrospective analysis was performed using data from a total of 427 patients with DVT treated with CDT in our single center between July 2009 and December 2012.Early efficacy of thrombolysis was assessed with a thrombus score based on daily venography.The therapeutic safety was evaluated by adverse events.A venography or duplex ultrasound was performed to assess the outcome at 6 months,1 year and 2 years postoperatively.Results:The mean total dose of 3.34 (standard deviation [SD] 1.38) million units of urokinase was administered during a mean of 5.18 (SD 2.28) days.Prior to discharge,Grade Ⅲ (complete lysis) was achieved in 154 (36％) patients;Grade Ⅱ (50-99％ lysis) in 222 (52％);and Grade Ⅰ (50％ lysis) in 51 (12％).The major complications included one intracranial hemorrhage,one hematochezia,five gross hematuria,and one pulmonary embolism.Moreover,no death occurred in the study.Conclusions:Treatment of low-dose catheter-directed thrombosis is an efficacious and safe therapeutic approach in patients with DVT offering good long-term outcomes and minimal complications.