A randomized double blind multicenter trial was performed to study the pharmacodynamic and clinical activities of 5682 SE, in comparison with diosmin (active principle) well recognised for many years. 5682 SE is a purified micronized flavonoid fraction containing 450 mg of diosmin and 50 mg of hesperidin per tablet. 90 patients with chronic venous insufficiency of the lower limbs stabilized for one year entered the study. They received either 2 tablets of 5682 SE or 900 mg of diosmin a day during two months. The following parameters were studied: functional clinical symptoms in the legs, ankle and calf circumferences measurements, strain-gauge plethysmographic parameters with 20, 40 and 60 mmHg venous occlusion, clinical and biochemical acceptabilities. In both groups of patients, the data showed statistically significant changes. But the improvement in the clinical symptoms and the decreases in the venous outflow parameters were more substantial with 5682 SE than with diosmin. The clinical and laboratory acceptabilities were equal in both groups. Due to its pharmacodynamic and clinical activities which are more considerable than those of non-micronized diosmin, the results of this study show the therapeutic advantage of 5682 SE in chronic venous insufficiency.