A sustained release system for aceclofenac designed to increase its residence time in the stomach without contact with the mucosa was achieved through the preparation of floating microspheres by the emulsion solvent diffusion technique. Floating microspheres were prepared using either Eudragit S 100 (ES) alone or with Eudragit RL 100 in different ratios. All formulation show good flow properties. The floating microspheres were found to be spherical by SEM. FT-IR study confirmed the drug-polymer compatibility. Although aceclofenac release rate from Eudragit S 100 floating microspheres was very slow and incomplete but when Eudragit RL 100 was added, release rate increased. Formulation AP6 containing ES:ERL (1.5:0.5) which showed appropriate balance between release rate and buoyancy could be advantageous in terms of increased bioavailability of aceclofenac. Therefore data obtained suggest that floating drug delivery system produced would be an interesting gastroretentive controlled release delivery system for aceclofenac. The prepared formulation will minimize the irritant effect of aceclofenac on the stomach by avoiding direct contact with the mucosa and providing a mean of low dosage for prolonged period.