Polylactide (PLA) and polylactide-co-glycolide ( PLGA) particles entrapping rotavirus (strain SA11) were formulated using a solvent evaporation technique. To minimize denaturation of viral antigen during the emulsification process, serum albumin was used as a stabilizer. Use of NaHCO(3) and sucrose during the primary emulsification step resulted in uniform stabilized particles entrapping rotavirus. Sonication during the primary emulsion and homogenization during the secondary emulsion process resulted in particles of sizes 2-8 mu m, whereas nanoparticles were formed when sonication was used during both primary and secondary emulsion processes. Scanning electron and atomic force microscopy showed uniform pores and roughness throughout the polymer particle surface. Single dose oral immunization with 20 mu g of antigen entrapped in PLA particles elicited improved and long-lasting IgA and IgG antibody titer in comparison to the soluble antigen. The study shows results illustrating the usefulness of polymeric microparticles as a potential oral delivery system for rotavirus vaccine.