Ion exchange resins (IER) are cross-linked water insoluble polymers that contain ionizable acidic or basic functional groups and have the ability to exchange counter-ions from surrounding within aqueous solutions. On the basis of nature of the exchangeable ion of the resin as a cation or anion, classified into two main classes, cationic exchange resinand anionic exchange resins, respectively. Due to versatile properties of IER, it has received considerable attention from worldwide pharmaceutical scientists. Research has shown that for the past few years, IER is equally suitable for drug delivery techniques, including controlled release, topical, transdermal, nasal and taste masking. The efficacy IER mainly depends upon their physical properties such as porosity, acid-base strength, degree of cross linking, stability, purity and particle size. Ion-exchange resinates (Drug-Resin complex) of drugs can help in reducing the dose, fluctuations in blood and tissue concentrations, avoiding dose dumping,  and maintenance of drug concentration below toxic level can be achieved. The major drawback of sustained release or extended release is dose dumping, resulting in increased risk of high dose toxicity. The utilization of IER has occupied an important place in the development of controlled or sustained release systems because of their better drug-retaining properties and prevention of dose dumping. Resins are polymers that contain appropriately substituted acidic groups, such as carboxylic and sulfonic for cation exchangers; or basic groups, such as quaternary ammonium group for anion exchangers. Drug resin complexation converts drug to amorphous form leading to improved drug dissolution. Many studies have reported the use of IER for drug delivery on the desired site of action. Sulfonated and carboxylic resins with a polystyrene backbone are mostly used in clinical medicine. This review will cover various types of ion exchange resin, their property, chemistry; The role of IER in controlled drug delivery systems, its Industrial, Pharmaceutical and clinical applications, methods of preparation of IER along with their resonates.