May-Thurner syndrome (MTS) is caused by venous occlusion because of compression of the iliac vein by the iliac artery and vertebral body, leading to left lower extremity deep venous thrombosis, eventually resulting in a series of symptoms. Endovascular treatment has now become the most preferred method of treatment of MTS. The authors report a 66-year-old woman who was hospitalized because of increasing swelling in her left lower limb for almost 2 weeks. Ultrasonography performed upon admission indicated MTS, and venography revealed occlusion of the left common iliac vein and massive thrombosis in the left external iliac and femoral veins. The left lower extremity venous blood flow returned to normal after the patient underwent manual aspiration thrombectomy using a guide catheter, followed by balloon angioplasty and stent placement. The patient achieved complete remission after 1 week and had no in-stent restenosis during the 1-year follow-up. Endovascular treatment is a safe and effective treatment of MTS.