Swelling is one of the most frequent complaints of patients in daily clinical practice; leg edema is its objective confirmation. It can be associated with several diseases. Micronized purified flavonoid fraction (MPFF) is a phlebotropic drug commonly used to treat the signs and symptoms associated with chronic venous insufficiency (CVI). It has confirmed its clinical efficacy in different groups of patients suffering from edema: idiopathic cyclic edema, CVI-associated edema, postmastectomy lymphedema and might be beneficial in some of drug-induced edema. In a double-blind, placebo-controlled, randomized study including 30 outpatients suffering from idiopathic cyclic edema syndrome, MPFF 1000 mg/day for 6 weeks, normalized the capillary permeability, assessed by the Landis isotope test, in 3 out of 4 patients (p=0.01). The decrease in capillary hyperpermeability led to a clinically significant decrease in weight and edema. In 200 patients with functional or organic venous insufficiency of the lower limbs, a double-blind, placebo-controlled, randomized study with MPFF 1000 mg/day for 2 months provided strong evidence of a marked improvement in symptoms and signs. A significant reduction in supramalleolar edema (assessed by circumference measurement) was observed, whatever the origin of CVI: functional or organic. MPFF efficacy was also demonstrated in another randomized, multicenter controlled trial in 320 patients suffering from chronic venous insufficiency. In this study, a significant decrease in circumference of the most affected leg was observed after 2 months of treatment (p<0.001), whatever the schedule of administration of MPFF (1000 mg once daily or bid). The benefit of MPFF on edema has been further confirmed by the volometer technique (opto-electronic measuring system) which was performed in a population of 30 patients suffering from CVI and treated by MPFF 1000 mg/day over a 6-week period. The mean volume of the more affected lower leg decreased significantly after a 6-week period of treatment, correlating to a significant improvement in clinical symptoms. MPFF has been also tested on another type of edema, upper limb lymphedema secondary to mastectomy, during a double-blind, placebo-controlled, randomized study in 104 patients. MPFF 1000 mg/day improved all lymphoscintigraphic parameters such as half-life and clearance of the labelled colloid. With regard to evolution of lymphedema volume, a tendency in favor of MPFF was observed in the subgroup of patients with more severe lymphedema. Based on its action on capillary hyperpermeability, MPFF has been used with attractive results when combined with classic treatment for a pilot study carried out in patients with advanced breast cancer (n=21) or ovarian carcinoma (n=3), treated with docetaxel, which causes severe edema as a side effect, even when associated with corticoids. Further trials are under way to assess the possible benefit of MPFF in such patients. These results in different types of edema confirm that, by acting on all parameters involved in edema, veins, lymphatics, and microcirculation, MPFF represents a drug of choice for treating CVI-associated edema.