- Over the ages, the use of leeches in medicine has evolved from haphazard bloodletting to a well-understood physiologic process with defined, rational applications. The authors describe the current role of leech therapy in cutaneous surgery and medicine. Case series and review of the literature. Leech saliva contains anticoagulative, anti-aggregative and vasodilatory components. Combined with the annelid's mechanical ability to extract blood, leeches can contribute to patients' health with minimal risks. Leeches should be considered as novel therapies for disorders of coagulation and venous congestion. Implementation of leech treatment should be tempered with the potential adverse effects, including Aeromonas infection and a drop in hematocrit that might require a blood transfusion.