Drug development is a very laborious and expensive process. One of the major reasons for failure during the clinical phases of drug development is inadequate pharmacokinetic data on the drug candidate. Therefore, it would be advantageous if the pharmacokinetic properties of drug candidates be predicted beforehand. One major obstacle in making such predictions is the inability to appropriately scale the in-vitro data to the in-vivo situation. Results from in-vitro in-vivo correlation (IVIVC)  studies have been used to select the appropriate excipients and optimize the manufacturing processes for quality control purposes, and for characterizing the release patterns of newly formulated immediate release, and modified-release products relative to the references. In recent years, the concept and application of the IVIVC for pharmaceutical dosage forms have been a major focus of attention in the pharmaceutical industry, academia and regulatory agencies. Hence, this article highlights the importance of appropriate selection of IVIVC level with respect to the Biopharmaceutical Classification System (BCS) and also covers examples of BCS-based IVIVCs of drugs/products with different types of release profiles.