Adventitial cystic disease of the femoral vein is an extremely rare condition; therefore, diagnosis, treatments, surgical approaches and long-term prognosis are not well defined. We report the case of a 67-year-old man with femoral vein adventitial cystic disease complicated with deep vein thrombosis. He presented with right leg oedema. Ultrasound, computed tomography and magnetic resonance imaging revealed a mass in the femoral vein, and deep vein thrombosis was not detected at the time. However, venous return disorder worsened due to the mass causing a deep vein thrombosis in the femoral vein, and anticoagulation therapy with edoxaban was administered. Subsequently, deep vein thrombosis in the femoral vein disappeared, but remained in the lower calf. The mass and femoral vein were completely resected and reconstructed with an expanded polytetrafluoroethylene graft. No recurrence was observed over 3 years and 3 months.