Abstract: In the present study biodegradable microparticles of chitosan were prepared by the simple water-in-oil emulsion solvent diffusion method for use as drug delivery systems. Aqueous chitosan solution and ethyl acetate were used as water and oil phases, respectively. Gentamicin sulphate was used as a hydrophilic model drug. Effects of drug content and sodium tripolyphosphate cross-linker on chitosan microparticles and drug release behaviors were investigated. The both drug-free and drug-loaded chitosan microparticles were deflated microparticles and porous structures with 200-400 μm in size. The cross-linking did not affect on microparticle shape and size. The drug release rates decreased as the drug content decreased and the amount of cross-linker increased.