To aid various pharmaceutical dosage formulations, synthetic, semi-natural or natural polymers have often been employed as additives for tablet binding and processing, as surfactants for emulsified products and as enteric coating materials. The polymer has recently been playing a more important role as a matrix in sustained or controlled release formulations. The enteric coating material, which is used to minimize stomach irritation, to protect acid labile drugs from harsh stomach condition or to mask unpleasant tastes, is a polyacid and so has the properties of being insoluble at acidic stomach pH but dissolving or swelling at intestinal pH. This is a well-known, traditional example of using the solubility transition of pHsensitive polymer (a smart polymer) in pharmaceutics. As understanding of technology in smart polymers, which alter their physicochemical properties in response to minute changes in environmental conditions, advances, challenges to novel concepts for drug delivery and new fabrication techniques in dosage forms have been introduced and progressed in the last two decades. Some attempts include entrapping protein drugs in a polymer matrix without using organic solvents, actively controlled drug release, self-regulating or episodic delivery systems, and injectable in situ drug depot. Most approaches are currently experimental; however commercial products based on the smart polymer technology are soon anticipated.