The objective of this study was to evaluate the effectiveness and safety of endovenous cyanoacrylate closure (CAC) of incompetent great saphenous vein (GSV) and to assess the regression of varicose vein following CAC without a concomitant procedure. A total of 63 limbs in 48 patients treated with CAC because of an incompetent GSV between December 2016 and November 2017 were retrospectively evaluated. In five limbs, incompetent GSV and small saphenous vein were treated simultaneously in the same session. Duplex ultrasound, Venous Clinical Severity Score, degree of regression of varicose veins, and adverse events were examined at intervals of 1 week, 1 month, 3 months, 6 months, and 12 months. In 63 limbs, of which 60 were available for follow-up, all treated GSVs showed complete closure during the follow-up period (8.4 ± 3.0 months). Venous Clinical Severity Scores at the time of all follow-up visits were significantly lower (P < .001) than those before CAC. Complete resolution of varicose veins was noted in 38 limbs (71.7%) after 3-month follow-up. The proportion of limbs showing >50% varicose vein regression reached 90.6%. The more that varicosity entry was covered (P = .002) and the farther down the leg the access site was located (P = .024), the more complete resolution of varicose veins was observed. Phlebitis occurred in 10 limbs (16.7%), and hyperpigmentation occurred in 8 limbs (13.3%). CAC is safe and effective for the treatment of an incompetent GSV. It also shows a satisfactory result with the regression of varicose veins. Covering the entry of varicosities and accessing lower down the leg are associated with more complete resolution of varicose veins. Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.