Chitosan extracted from shrimp cortex was grafted with some different anhydride compounds like; acetic anhydride, propionic anhydride, succinic anhydride, and phthalic anhydride. The chitosan-grafted-anhydrides were copolymerized with L-lactide in ring opening polymerization. All grafted chitosan derivatives were obtained in very good yield, and they were characterized by FTIR and the resulted spectra confirmed the right structures of chitosan and its different synthesized derivatives, and then they were converted to nanoparticles in size by subjecting them to sonication method.In vitro cytotoxicity detection of different chitosan anhydride derivative nanoparticles and their grafted-polylactide were concerning three different types of human breast cancer cell lines as MTT assay, the results exhibit the highly significant cell growth inhibition of these tumor cells compared with a positive control; furthermore, the chitosan anhydride derivatives grafted polylactide demonstrated increasing in reducing cell viability in comparison with their non-grafted form. The DNA fragmentation index percentage was evaluated for some of the studied polymer nanoparticles, using acridine orange dye and the results were shown no or less effective against BT breast carcinoma cell lines DNA