Catheter directed thrombolysis is a minimally invasive procedure that results in a significant reduction in venous obstruction after deep vein thrombosis. The technique implies the performance of phlebographies to monitor the thrombolysis progression. The objective of this paper is to describe the use of vascular ultrasound to follow the thrombus lysis and to adjust the catheter position according to the progression of the thrombolysis. This is the first case reported describing the application of ultrasound to monitor the thrombolysis. A 36-year woman was admitted ilio-femoral vein. The ipsilateral great saphenous vein was the percutaneous access to perform the anterograde thrombolysis. The procedure, including the control of thrombus lysis, as well as catheter progression was performed under ultrasound guidance. The thrombolysis took 52 hours. The patient has two years of follow-up without any complaint. The use of vascular ultrasound to monitor the thrombolysis has several theoretical advantages in patients with adequate biotopes. It minimizes the number of venograms and can be performed at the bedside. It is effective and inexpensive.