Therapeutic effectiveness of a drug depends upon ability of the dosage form to deliver the medicament to its site of action at a rate and amount sufficient to bring out the desired pharmacological response. Bioavailability is the first and foremost prerequisite for elucidate the therapeutic response and/or toxicity of any drug and/or drug product. This book emphasize on Bioavailability and bioequivalence, factors affecting drug absorption and bioavailability, biopharmaceutical considerations in dosage form designing, methods to determine BA and BE and technologies to improve the dissolution of poorly soluble drugs.