<p>The goal of this study is to collect allicin from garlic and evaluate its protective role against arsenic induced toxicity. To conduct this study, allicin has been quantified and collected from ethanolic extract of garlic by High-Performance Liquid Chromatography using C₁₈ column at 254&#xa0;nm wave-lengths against standard allicin at the retention time of 18.775&#xa0;min. Calculated concentration of allicin is 77.80%. This allicin fraction showed dose dependent gradual increase of antioxidant activity with half- maximal inhibitory concentration (IC₅₀) value of 2.37&#xa0;mg/ml on 2,2-diphenyl-z-picrylhydrazyl radicals. A comparative study of haematological and nephro-protective role of garlic and allicin fraction have been done using <i>Swiss</i> albino mice (<i>Mus musculus</i>) as in vivo model. For these study major haematological parameters like haemoglobin (Hb), red blood cell, white blood cell, packed cell volume, and mean corpuscular haemoglobin concentration were counted and found increased by arsenic toxicity. In case of garlic and allicin co- treatment those parameters significantly (<i>p</i> &lt; 0.05) reduced. Kidney weight, total protein and marker enzymes of kidney were estimated after 30&#xa0;days experimental period where garlic and allicin co-treatment significantly increase kidney weight and total protein and reduced blood urea nitrogen and creatinine level (<i>p</i> &lt; 0.05). Histological slides of kidney of different sets were considered to measure the intensity of arsenic trioxide induced oxidative stress and protective role of garlic and allicin. Generated data pointed out that both garlic and allicin fraction offer significant protection of kidney and haematological parameters over arsenic toxicity but allicin fraction offers higher protection.</p>