The aim of this study is to compare two ultrasound guided foam sclerotherapy (UGFS) techniques to great saphenous vein (GSV) by injecting the sclerosant foam through a short catheter without perivenous tumescence and through a long catheter with saline anesthetic tumescence. Method: selection of 50 patients with primary varicose veins, edema (C3EpAsPr of the CEAP classification) and with GSV measuring 6 - 10 mm, 3 cm below the saphenofemoral junction, identified by ultrasound. The study is taking place at the vascular surgery ambulatory of the University of São Paulo. It is a prospective controlled trial with random allocation in two groups according to the foam sclerosant technique injection. The group 1 will receive the sclerosant foam by a short catheter 18 G and in the group 2 an angiographic catheter 4 Fr. will be used. All patients will be treated with 3% polidocanol foam prepared with a three-way tap and two plastic disposable syringes, according to Tessari's method. The access will be by puncture and its place will depend on the insufficient venous extension. It will be at the level of the knee to treat proximal GSV or at the medial ankle to treat the full length of the vein. In group 2, after inserting the long catheter into the GSV, a saline anesthetic solution will be infiltrated around the insufficient venous segment under ultrasound guidance to reduce its diameter. The long catheter will be continuously flushed with 0.9% saline solution until the foam sclerosant injection. In the cases of treating only the proximal GSV, patients will receive a continuous compression with tourniquet below the knee just before the injection and maintained for 5 minutes thereafter. Then, the tributaries in all 50 patients will be treated by phlebectomy under tumescent local anesthesia. Color-duplex ultrasound follow-up is programmed to 7, 28 and 168 days after the treatment. The first one is to check the possibility of deep venous thrombosis, the second is to verify the occlusion rate and the need of another foam injection. The last ultrasound is to check the final occlusion rate.