The performance of poly(DL-lactide-co-glicolide) (PLGA) nanoparticles without surfactant or emulsifiers was investigated by a dialysis method. The size of the PLGA nanoparticles prepared from dimethylacetamide (DMAc) as an intial solvent was smaller than that from acetone. The size of the PLGA nanoparticles from DMAc and acetone were 200.4 133.0 and 642.3 131.1 nm, respectively. the efects of initial solvent selected to dissolve the copolymer and the lactide:glycolide ratio were investigated. The PLGA nanoparticles were spherical as revealed by the results of scanning electron microscopy and transmission electron microscopy observations. from these results it was shown that PLGS nanoparticles could be fromed by the dialysis method without surfactant. The drug-loading contents and efficiency were also dependent of the lactide:glycolide ratio and initial feeding amount of the drug. A higher lactide ratio resulted in the higher drug loading and higher loading efficiency, However, a higher initial feeding amont of the drug resulted in higher drug loading and lower loading efficiency.