Microparticles are one of the key novel drug delivery systems has been widely used to precisely modulate release rate. Microparticles based polymeric systems fabricated using suitable carrier has been extensively explored as an effective matrix for controlled and sustained release delivery of many drugs. With the controlled release systems, the rate of drug release matches the rate of drug elimination, and therefore the drug concentration is within the therapeutic window for the majority of the 24-hr period.The aim of this study was to prepare Eudragit microspheres containing Tramadol HCl by solvent evaporation method to achieve a controlled drug release profile. Investigation of the effect of various processing and formulation factors such as polymer type, drug: polymer ratio, stirring speed to obtain spherical particles. Then yield of production, shape, and mean particle size, particle size distribution, encapsulation efficiency, surface properties and release rate of drug from the microspheres were performed.