The purpose this review on floating drug delivery systems (FDDS) was to compile the recent literature with special focus on the principal mechanism of floatation to achieve the physiological and formulation variables affecting gastric retention, approaches to design Effervescent and Noneffervescent floating systems, and their classification and formulation aspects. It is known that differences in gastric physiology (such as, gastric pH, motility) exhibit both intra- as well as inter-subject variability demonstrating significant impact on gastric retention time and drug delivery behavior The floating or hydrodynamically controlled drug delivery systems are useful in such application. From the formulation and technological point of view, the floating drug delivery system is comparatively easy and logical approaches are discussed.