Medicinal leeches (Hirudo medicinalis, Hirudo verbana) have been used in the field of medicine to treat various diseases for thousands of years. Popularity of their use changed over time and in Europe, it peaked at the beginning of the 19th century. In modern medicine, application of leeches on flaps with venous congestion was first used and described by Deganc and Zdravic in 1960. A certain renaissance of leech use is currently taking place, especially in the field of reconstructive surgery. In general, use of leeches is indicated during critical post-operative period, in which the microcirculation and veins are incapable of sufficient drainage of venous blood, which can lead to stagnation of circulation in tissues at all levels, clinically manifested as a change in color and turgor of the flap. If this venostasis is not recognized in time and treated adequately, tissue necrosis can develop. Medicinal leeches can be used in venous drainage disorders after a replantation of fingers, auricles, lips and parts of the nose. In head and neck reconstructive surgery, there are many studies that confirm the success rate of hirudotherapy in hematoma evacuation or in dealing with complications after scalp replantation and transfers of free and pedicled flaps. Leech application therapy can also be indicated as a part of non-surgical methods that improve conditions of the venous system.