Bioavailability studies are critical studies used to support INDs and NDAs. BA refers to the rate and extent to which the active ingredient or active moiety is absorbed from a drug product and becomes available at the site of action. This data is used to determine the fraction of drug absorbed and a drugs pharmacokinetics. FDA’s guidance focuses on the use of pharmacokinetic studies to document bioavailability data. Specifically, FDA provides recommendations on type of study, population composition, dosing, analytical methods, measures of systemic exposure, and other approaches to support bioavailability. To deliver many drugs to their site(s) of action, we rely on the systemic blood circulation, as opposed to locally acting drug products, such as ointments intended to treat a skin condition. For drug products intended for systemic absorption, bioavailability of a drug from its dosage form is generally determined by comparing its pharmacokinetic profile in blood with that after intravascular administration of the same drug in solution. The present study was aimed to study the need for bioavailability studies, ethical guidelines, experimental designs, pharmacokinetic endpoints, and their statistical evaluations. Specifically, the guidance addresses study design considerations, including in-vivo and in-vitro studies, and assessing BA for various dosage forms. Appendices provide recommendations for approaches for general study design and data handling, guidelines for conducting fed or fasted studies, and guidelines for conducting an in-vitro alcohol dose-dumping study.