Pharmacokinetics derived from the Greek words pharmakon (drug) and kinetikos (movement), is employed to explain the absorption, distribution, metabolism, and excretion of a compound. Although preclinical studies require the determination of acceptable in vitro activity and pharmacokinetics in a minimum of two animal species, pharmacokinetic studies must be performed in man to correlate blood concentrations with particular biological effects. Knowledge of disposition in vivo is required to tailor modifications so as to eventually derive semisynthetic drugs. Pharmacokinetic studies of natural products are challenging because they typically involve the administration of complex mixtures of gear, in many instances of unknown components. Some Chinese medicines including Danshen (Salvia miltiorrhiza), Kang-lai-te (Coix lachryma), and Ginkgo bilboa are evaluated in randomized controlled clinical trials [1]. Many pharmacokinetic parameters, particularly of poisons, haven't yet been determined as even in vitro studies are hindered by the acute toxicity of some poisons, like palytoxin. Pharmacokinetics could also be defined because the study of the dynamic movements of foreign chemicals (xenobiotics) during their passage through the body and in and of itself encompass the kinetics of absorption, distribution, biotransformation/metabolism and excretion (ADME). It can simply be described as how the body handles xenobiotics. Pharmacokinetics uses mathematical equations (models) to explain the time course of ADME of xenobiotics within the body enabling us to raised understand, interpret and even predict the character and also the extent of the biological effects (therapeutic or toxic) of xenobiotics. Several approaches are employed in pharmacokinetic to explain the fate of xenobiotics within the body, including considering the body united or more homogenous compartments based either on mathematical fitting or physiological properties. Description of the rates of the movement of xenobiotics into tissue(s) allows better interpretation and prediction of the fate of xenobiotics inside the body. this text will introduce the reader to basic concepts and principles of pharmacokinetic analysis using both compartmental and physiologically based models.