Chitosan grafted with macrocyclic polyamines (Cs-g-MCPA) on the C-2 or the C-6 position was synthesized by a simple method. Four copolymers prepared were characterized by (1)H NMR, (13)C NMR, Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), and gel permeation chromatography (GPC). Circular dichroism spectra (CD), fluorescence spectra and agarose gel electrophoresis assay showed that Cs-g-MCPA copolymers had good binding ability to DNA. By modification of the MCPAs, the copolymers showed low cytotoxicity and high transfection efficiency as new gene vectors. It was found that Cs-g-MCPA copolymers with different grafted positions showed different properties: copolymers grafted on the C-2 position showed higher cytotoxicity and higher transfection efficiency than those grafted on position C-6.