The gastric emptying process drastically reduces the bioavailability of drugs that target the stomach for their action. A gastro retentive drug delivery system (GRDDS) becomes a solution to retain drugs in the stomach and release drugs from the formulation system within a certain period. The polymer used in the GRDDS formulation is the essential excipient that can retain the drugs in the stomach. Several ways for GRDDS to maintain its existence in the stomach are using some systems, such as mucoadhesive, low-density, high-density, swellable, eff ervescent, and expandable systems. A polymer is a macromolecular substance with a long repeating chain consisting of natural and synthetic polymers, each with diff erent potentials. It is considered for its ability to regulate drug release, good fl ow properties, can improve drug dissolution to improve bioavailability and stability during processing in the body. Combining natural and synthetic polymers is often carried out to obtain advantages and cover the existing polymer’s disadvantages. Polymers can release drugs using three diff erent mechanisms, i.e., diff usion, degradation, and expansion. These techniques are often chosen for the formulation of GRDDS because of their more fl exible system and fi t for almost all types of GRDDS. The polymer used in the GRDDS system is chosen from its physicochemical properties and the number of fl oating times, drug release rate, viscosity, fl oating lag times, bioavailability, and solubility.