10.22376/ijpbs.2019.10.1.p1-12 Volume 6 Issue 3 2015 (July - September) The present study deals with the formulation of gastroretentive hollow microsphere of Acyclovir using Eudragit RS 100 & Ethyl cellulose as a polymer & solvent (Ethanol & Di chloro methane) in different ratio of solvent evaporation method. A number of evaluation parameter was carried out. A drug – exicipient compatibility studies was performed by FTIR. Microspheres were evaluated for particle size, micromeritic properties, flow property, drug entrapment efficiency, in vitro drug release , kinetic studies. The shape & size of microsphere were carried by Scanning Electron Microscopy. CHARU SAXENA Acyclovir, Eudragit, Ethyl cellulose, microsphere 262-278