Abstract: Objective To investigate how malignant tumor complication affects the therapeutic efficacy of thrombolysis and anticoagulation to treat acute lower limb deep venous thrombosis（DVT）. Methods A total of 34 patients with acute lower limb DVT complicated by malignant tumor and 34 patients with acute lower limb DVT following an operation or injury were recruited.Both groups were treated with conventional therapy of thrombolysis and anticoagulation，and the effects of the malignant tumor complication on therapeutic efficacy were assessed. Results The recanalization rate and effective therapeutic rate were lower in the group with a malignant tumor complication than in the group without it（P<0.05）. Conclusions Conventional therapy is not effective for treating acute lower limb DVT complicated with malignant tumor.

Key words: Malignant tumor, Deep venous thrombosis （DVT）, Therapeutic effect