The purpose of this study was to prepare and characterize controlled release ketorolac tromethamine microparticles. To achieve this goal, Eudragit RS100 microparticles loaded by ketorolac tromethamine were prepared by the emulsion solvent evaporation method. The prepared ketorolac tromethamine microparticles were evaluated for their production yields, particle size distribution, morphology, drug content and drug release characteristics. Thermal Gravimetric Analysis (TGA) was performed on the drug polymer systems in order to shed a light on the possibility of solid state changes of ketorolac tromethamine with Eudragit RS100. Via the emulsion solvent evaporation technique applying Box-Behnken design to choose these formulae. Box-Behnken design determined fifteen formulae containing specified amounts of the independent variables, which included revolution per minute (X1), drug: polymer ratio (X2) and span 80 percent (X3), the dependent variables studied were cumulative percent release after two hours (Y1), four hours (Y2) and eight hours (Y3).The prepared micro particles were characterized for their production yield, sizes, shapes and morphology, entrapment efficiency and ketorolac tromethamine in vitro release as well. The results showed that the production yield of the prepared ketorolac tromethamine microparticles was found to be between 77.80% and 93.66%. The formulated microparticles exhibited acceptable drug content values that lie in the range 53.24%-8018%. Also, the data obtained revealed that increasing the mixing speed (X1) generally resulted in decreased microparticles size. Kinetic treatment of the in vitro release from drug-loaded microparticles indicated that there is no one kinetic order can explain the release of KT-Eudragit RS100 capsules.