Objectives: Allicin is an organosulfur compound featuring thiosulfinate functional group. The compound is formed in garlic after tissue damage, by the action of enzyme alliinase on alliin. This study involves extraction of allicin from garlic using high-performance liquid chromatography (HPLC) and study of it is the genotoxic effect on human leukocytes. Methods: A simple and rapid reverse phase HPLC was used for the extraction of allicin. Quality allicin, in conjugation with chymosin, was used to study its genotoxic effect on leukocytes. Results: Garlic oil and garlic extract showed similar retention time, and we measured the products using genotoxic effects in human leukocyte culture and it shows statistically not significant. Conclusion: This study suggested that to take a lower concentration of garlic extracts benefits for health and these findings useful for further research. © 2015, Asian Journal of Pharmaceutical and Clinical Research. All rights reserved.