Flavonoids are herbal medicines and widely used for chronic venous diseases and hemorrhoids. Flavonoid diosmin in both micronized and non-micronized form is a part of various drugs. According to literature data, flavonoids are able to reduce venous stasis, suppress local inflammation, improve venous tone and lymphatic outflow. It should be noted that biological models of in vivo trials have certain limitations while available data of different researches are contradictory. However, flavonoids were recommended for hemorrhoids in view of meta-analysis of 14 trials comparing flavonoids (diosmin, micronized purified flavonoid fraction and rutosides) with placebo in 1514 patients with hemorrhoids and Cochrane review of 24 randomized controlled trials (2,334 participants). These drugs should be administered as a part of complex therapy. At the same time, there is no conclusive evidence to prefer only one of these medicines. There are also no data confirming the benefits of daily dosage of 3000 mg per day of micronized fraction of flavonoids compared with 1800 mg of purified diosmin per day for treatment of acute hemorrhoids.