Background & Aim: Today, the use of medicinal plants has been growing because of less side effects than chemical drugs in the treatment of diseases particularly infectious diseases. According to the available scientific evidence, garlic is an effective anti-parasitic drug. In the present research will be study the inhibitory effect of garlic tablet on Limnatis nilotica. Material & Methods: To study the garlic tablet effect on paralysis and mortality of leech Leeches were placed in plastic vessels containing 600 ml of water and adding ground garlic tablet 400, 800, 1200 mg. From 1 to 4 hours after the exposure paralysis and death rate of the leeches were recorded accurately. Results & Discussion: The results indicated no effect of garlic tablet on motor response and mortality rate of the leeches. This problem probably caused by removal of thiosulfinate group of garlic tablet. Conclusion: This Study confirming the role of thiosulfinate compound to cause anti-parasitic property of garlic. Possibly, extract of garlic can be effective for leech infestation due to thiosulfinate compound. پرونده مقاله