The objective of this investigation was to develop the hollow microspheres as a new dosage form of floating drug delivery system with prolonged stomach retention time. Hollow microspheres containing ranitidine hydrochloride were prepared by solvent evaporation method using Eudragit RLPO dissolved in a mixture of dichloromethane and ethanol. The maximum yield and drug loading amount of hollow microspheres were 88.45% and 80 +/- 4.0%, respectively. The in vitro release profiles showed that the drug release rate decreased with increasing viscosity of Eudragit RLPO, while diameter of hollow microspheres increased with the increase of drug polymer weight ratio. Hollow microspheres could prolong drug release time (approximately 24 h) and float over stimulate gastric fluid for more than 12 h. These results demonstrated that ranitidine HCl hollow microspheres were capable of sustained delivery of the drug for longer period with increased bioavailability.