Pharmacokinetic and toxicokinetic studies provide useful information, which facilitates assessment of safety of the chemical entity. The design and analysis of pharmacokinetic and toxicokinetic studies requires a broad understanding of the underlying concepts and principles inherent in the ADME process. This article describes basic concepts of ADME and practices of studies conducted to study it as described in regulations of the EPA and Organisation for Economic Co‐operation and Development (OECD).