Horse- chestnut seed extract is widely used throughout Europe, and has been used to treat a variety of medical conditions. The most common indication is currently chronic venous insufficiency, for which conventional therapy includes use of compression stockings. Horse chestnut seed extract is generally well tolerated; the most common side effects are gastrointestinal disturbances, dizziness and calf-muscle spasms. Clinical trials have shown that horse- chestnut seed extract and placebo are associated with similar side effects Horse- chestnut may interact with anticoagulants and antidiabetics, and caution is advised in patients taking these drugs. A number of clinical trials have shown that horse- chestnut seed extract may be beneficial to patients with mild to moderate chronic venous insufficiency. However, inadequate randomization, short duration and use of different end-points in these trials makes it difficult to conclude regarding effectiveness and safety, especially in long-term use. Horse- chestnut seed extract appears to be a short-term treatment option in patients with mild to moderate chronic venous insufficiency, but more rigorous trials are required to confirm the efficacy of this treatment.