Chitosan microspheres loaded with indomethacin were prepared using only aqueous solvents. The influence of formulation variables on indomethacin content in the microspheres and time for release of 66.6% of indomethacin from the microspheres was investigated. Amongst various variables, the indoemthacin:chitosan ratio and amount of crosslinking agent were important. Response surfaces were generated to optimise the aqueous process with respect to these critical variables, in order to obtain maximum indomethacin loading and optimum t66.6.