Chitosan microspheres (CM) and reacetylated chitosan microspheres (ACM) were successfully made by the methods of oil/water emulsification and acetic anhydride. The characteristics of the microspheres as a drug carrier system were investigated. Two microsphere samples had spherical shape with the mean diameter of 80.79 microm for CM and 81.25 microm for ACM. The in vitro degradation (pH 7.4) in the presence of lysozyme showed a slow mass loss and ACM was higher degradation compared to CM. The microspheres, especially ACM, had a high drug loading capacity of Adriamycin hydrochloride (ADM) (12.4%) and had sustained release. The cytotoxicity was evaluated in vitro via MTT assay, ACM with steadily continual adhesion to cells had no fibroblast cytotoxicity. The inhibitory rates of ADM-loading CM, ACM suspension to Tca 8113 cells were significantly outperformed that of ADM solution.