Superficial vein thrombosis (SVT) most commonly involves the greater and lesser saphenous veins. Risk factors for SVT parallel those for deep vein thrombosis (DVT): varicose veins, thrombophilia, oral contraceptive use, immobilization, malignancy, direct trauma, and a history of thromboembolism. In this prospective study, Binder et al demonstrate that 9% of patients with sonographically proven SVT had a concomitant DVT. The DVTs were mainly asymptomatic, usually in the SVT-affected leg, and associated with elevated D-dimer levels, leading the authors to conclude that the deep veins should be assessed by color-coded duplex sonography when an SVT affects the lower leg. Evaluation of the contralateral leg is also suggested in cases of SVT with a substantially elevated D-dimer level and any symptoms of DVT.