Floating matrix tablets were designed and evaluated. Theophylline was used as a model drug. The system was prepared by mixing drug, matrix-forming polymer (hydroxypropyl methylcellulose, HPMC) and fillers together. The blended powder was compressed by hydraulic press. The effect of formulation variables such as type of matrix forming polymer (HPMC K100LV, HPMC K4M, HPMC K100M), amount of effervescent agent (0, 20, 30, 40% w/w) and compression force (0.5, 1 ton) on floating properties and drug release of floating matrix tablets were investigated. The results demonstrated that type of polymer affected floating properties of the floating matrix tablets. The floating matrix tablets prepared from lower viscosity HPMC (HPMC K100LV) showed faster drug release than those prepared from higher viscosity HPMC (HPMC K4M, HPMC K100M). Increasing amount of effervescent agent decreased time to float and increased drug release from the floating matrix tablets. Higher compression force did not affect time to float but decreased drug release from the floating matrix tablets. According to these results, floating properties and drug release of the floating matrix tablets could be modified by formulation variables. Some floating tablet formulations developed in this study showed good floating properties (time to float less than 15 minutes, floating time more than 8 hours) with sustained release as required. The system is promising as a carrier for gastroretentive drug delivery systems.