Polymers in oral drug delivery systems can be regarded as unique types of biomaterials. Their availability, regulatory acceptance, and unique physicochemical properties make them an indispensable tool in developing various types of oral drug delivery devices. Their application in oral drug delivery ranges from those specific to the manufacturing process to those involved in modifying drug release. The focus of this chapter will be on introductory information for commonly used polymers and their role in common oral dosage forms.