Allium sativum (garlic) has been recognized not only as a spice but also as a substance which exerts a control on microorganisms. Recent publications indicate that garlic extract has broad-spectrum antimicrobial activity against many genera of bacteria and fungi. The active component (allicin) has been isolated and characterized. Because many of the microorganisms susceptible to garlic extract are medically significant, garlic holds a promising position as a broad-spectrum therapeutic agent. Furthermore, garlic plants may also play an important role in the ecological control of pathogenic microorganisms in nature.