Dihydroartemisinin (DHA)-loaded methoxy poly(ethylene glycol)/poly(l-lactic acid) (mPEG5000PLLA3200) amphiphilic block copolymeric micelles (DHA-CM) have been prepared using modified solvent evaporation method. Physicochemical properties of DHA-CM were investigated by using dynamic light scattering, transmission electron microscopy, high-performance liquid chromatography, and Fourier transform infrared. Polymers formed stable, spherical, and worm-like micelles with mean sizes smaller than 130 nm. In vitro release experiments revealed that DHA-CM provided a more solubilizing effect than DHA suspension; in addition, it was showed that drug release profiles highly depended on pH values of dissolution media. Various types of lyoprotectants were tested to improve the redispersion performance of the freeze-dried products. 3-(4, 5-dimethyl- thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay was used to evaluate the cytotoxicity of micellar solutions of freeze-dried DHA-CM. The results showed that the IC50 values of DHA-CM and DHA suspension for KB cell lines were 18.70 and 24.55 M, respectively. However, DHA-CM had little cytotoxicity for L02 cell lines. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013