Over the recent years, interest has grown in using in-vitro and in-situ methods to predict as early as possible in-vivo oral absorption potential of a drug, to determine the mechanism and rate of transport across the intestinal mucosa and to alert the possible windows of absorption and also possible restrictions to the formulation approach. Since human in-vivo studies are not feasible, this prediction is of considerable interest at an early stage of drug development. This book is meant to provide an overview on various in-vitro and in-situ models for the study of drug transport, with an emphasis on in-situ perfusion and cell culture techniques, and data generated for each model for drugs with a broad range of physicochemical properties.