Throughout history, many different cultures have recognized the potential use of garlic for prevention and treatment of different diseases. Recent studies support the effects of garlic and its extracts in a wide scale of applications. Antioxidant activity of Garlic (Allium sativum) destroy free radicals particles that can damage cell membranes and DNA. Various preparations of garlic, specially aged garlic extract (AGE), have been shown to have promising antioxidant potential. However, the presence of more than compound in garlic, with apparently opposite biological effects, has added to the complexity of the subject. Raw garlic homogenate has been reported to exert antioxidant potential but higher doses have been shown to be toxic to the heart, liver and kidney. The aim of this review was to clear the difference between Garlic preparations with special references to their bioactive constituents, antioxidant potential and toxicity of Garlic