Allium sativum (Liliaceae) commonly known as garlic or lahsun is a medicinal plant, used in Ayurveda for treating various diseases, like hypertension, hyperlipidemia and diabetes mellitus. In this an effort has been made on the normal rats ; to study the pharmacokinetic interactions of Metformin (320mg/kg) with Allium sativum . The garlic extract (500mg/kg) was administered alone and along with allopathic drugs (MET) so that blood glucose lowering effect can be studied by administrating them orally to rats. Also alteration in absorption, metabolism, distribution and excretion of the drug are the causes of pharmacokinetic interactions; were studied. Plasma concentration of Metformin was analyzed by HPLC. Plasma concentration – time curve was plotted, and the peak plasma concentration (Cmax) and time needed to reach the peak plasma concentration (Tmax) were noted directly from the generated data. The area under the plasma level – time curve (AUC0-12h) was calculated using Trapezoidal rule. The elimination rate constant (Kel) was calculated from the semi-log plot of the data using slope of the terminal elimination phase; and half-life (t1/2) was calculated by 0.693/Kel and results were analyzed using one-way ANOVA to determine the significant difference in the pharmacokinetic parameters of Metformin between control and test group on 0th and 8th day. Significant changes were noticed in blood glucose.