The present study investigates vancomycin microencapsulation in biodegradable PLAGA microparticles. To optimize encapsulation efficiency by the double emulsion (w/o/w) solvent evaporation/ extraction process, two parameters were studied: surfactant (Span(R) 80) rate and external aqueous phase saturation. In vitro dissolution studies, laser granulometry and scanning electron microscopy were performed to characterize the microparticles. The best results were obtained by stabilizing the first emulsion with 0.5% Span(R) 80 and saturating the external phase with sodium chloride. Such parameters allowed a 95% drug encapsulation efficiency. This process yielded round microparticles with a mean diameter of similar to 170 mu m and presenting a smooth surface without any pores. Moreover, this formulation induces a sustained drug release at a constant rate over a period of 10 days. Such materials could be associated with biphasic calcium phosphate granules to form an antibiotic-loaded injectable bone substitute offering a long-term activity in situ.