Varicose veins (VVs) mostly represent benign disease. However, in some cases, they can lead to serious complications including deep venous thrombosis (DVT) and pulmonary embolism (PE). Besides deteriorated blood flow caused by VVs inflammation is most probably a common denominator of VVs and DVT, which promotes a procoagulant state and thrombus formation also in deep veins. Patients with VVs have increased levels of interleukins, the most specific inflammatory markers of vascular wall inflammation that promote coagulation. The studies showed that VVs may increase the risk for DVT. However, the evidence of the risk and incidence of DVT in patients with VVs and without additional risk factors is poor. The increased risk is associated with previous venous thromboembolism (VTE), malignancy, estrogen use, pregnancy and postpartum, hospitalization in the last 6 months, age, and obesity. Varicose veins represent also an increased risk for VTE during long-term immobilization and long air travel or road trip. Further, superficial venous thrombosis is related to an increased risk for DVT, particularly if the thrombus in the superficial vein extends close to the saphenofemoral or femoropopliteal junction. Increased risk for DVT is increased during and after invasive treatment of VVs. Thromboprophylaxis after invasive procedures is recommended in subjects older than 60 years and those with another thrombophilic state.