Chronic venous insufficiency (CVI) affects a large number of people in Western countries, and is responsible for considerable inconvenience, discomfort, suffering, and costs. Micronized purified flavonoid fraction (MPFF, 450 mg diosmin plus 50 mg hesperidin-Daflon 500 mg) is a potent venotropic drug used in the treatment of venous insufficiency. Pharmacological and clinical studies demonstrated the comprehensive mode of action of Daflon 500 mg: it increases venous tone, it improves lymph drainage, and it protects the microcirculation. Clinical international, prospective, multicenter, randomized, controlled studies versus placebo studies documenting the effects of Daflon 500 mg in CVI at advanced stages with edema, skin changes, and venous leg ulcer are reviewed. In edema, one of the most frequent complaints of patients, Daflon 500 mg brings about a significant reduction in leg circumference, thanks to its capacity to inhibit inflammatory reactions and to decrease capillary hyperpermeability. The rationale for the use of Daflon 500 mg for treatment of skin disorders and venous leg ulcer is its action on the microcirculation-damaging processes. Regarding skin changes, Daflon 500 mg has been shown to improve venous trophic disorders, like gravitational (stasis) dermatitis, and dermatofibrosclerosis. In venous leg ulcer, Daflon 500 mg's clinical efficacy has been demonstrated in addition to standard treatment or versus standard treatment alone. Daflon 500 mg, thanks to its comprehensive mode of action on the veins, lymphatics, and microcirculation, is the method of choice not only in the early stages of CVI treatment, but also in the severe stages of this condition, in combination with compression treatment, sclerotherapy, and surgery if appropriate.