56PHARMACEUTICAL ION EXCHANGE RESINS – A REVIEWIon exchange resins are water insoluble cross-linked polymers containing a salt-forming group at repeating positions on the polymer chain and have the ability to exchange counter-ions within aqueous solutions surrounding them. About 90 % of all ion exchange resins are based on a polystyrenic matrix. Synthetic ion exchange resins are usually cast as porous beads with considerable external and pore surface where ions can attach. Strong acid resins are so named because their chemical behaviou r is similar to that of a strong acid. These resins are highly ionized in bo th the acid (R-SO 3H) and salt (RSO3Na) form of the sulfonic acid group (-SO 3H). Ion exchange is a process in which mobile ions from an external solution are exchanged for ions that are electrostatically bound to the functional groups contained within a sol id matrix. There are various pharmaceutical grade resins like AMBERLITE® IRP88 , DUOLITE™ AP143/1083, INDION 204 , INDION 264 , TULSION® 335 TULSION® 345 , Kyron T etc. used as tablet disintegrant, active ingredients, as carrier for basic (cationic) drugs, application with compatible coating technique, mask objectionable taste associated with certain basic drugs, potassium reduction in blood, cholesterol reduction in blood, reduction of bile acid, treatment of hyperkalaemia and Stabilization of vitamin B12. This review covers the IER structure, chemistry, kinetics, ion exchange process, , loading of drug on resin, pharmaceutical grade resins ,drug delivery applications etc.ajay_bilandi2001@yahoo.comReview422014 Ion Exchange Resins,Cross-Linked Polymers,Pharmaceutical Grade Resins,Sustained Release,Taste MaskingAjay Bilandi,Amiya Kanta MishraResearch Scholar at Bhagwant University, Ajmer, Rajasthan, India.,Principal, College of Pharmaceutical Sciences, Puri, Orissa, India