Inferior vena cava (IVC) agenesis is a rare congenital vascular anomaly that may predispose young individuals to venous thromboembolism in the absence of classical risk factors. We report the case of a 35-year-old man, an active smoker with no significant medical history, who presented with a 10-day history of bilateral lower limb swelling and severe back pain radiating to the lower limbs. Doppler ultrasonography demonstrated extensive bilateral deep vein thrombosis (DVT), involving the right ex