In this study, the use of biodegradable polymers for microencapsulation of aceclofenac using solvent evaporation technique was investigated. Poly lactic acid was selected as a retardant polymer because of its advantages over other biodegradable polymers. Four different batches of microspheres were prepared by varying the concentration of polymer from 50% to 80% w/w. The microspheres were characterized for drug content, percentage yield and encapsulation efficiency, particle size analysis and surface morphology. Microsphere prepared with high drug content produces higher percentage yield and encapsulation efficiency values. It was observed the increase in concentration of the polymer, increases the mean particle size of the microspheres. The effect of polymer concentration on the in vitro release of aceclofenac from the microspheres was also studied. It can be seen that by increasing the polymer concentration, decreases the rate of drug release from the microspheres dramatically. The kinetics of drug release from F1 and F2 microspheres predominantly follows Higuchi pattern followed by zero order and then first order. The release kinetics of F3 and F4 predominantly follows zero order followed by Higuchi and then first order.