In the present work, chitosan (CS)-grafted multiwalled carbon nanotube (MWCNT) nanocomposites were prepared via covalently bonded CS onto MWCNTs that had weight fractions of MWCNTs ranging from 0.1 to 3.0 wt % by a simple method of solution casting. The structure, morphology, and mechanical properties of the films were investigated by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, optical microscopy, wide-angle X-ray diffraction, contact angle, and tensile testing. The results indicated that the CS chains were attached onto the MWCNTs successfully via covalent linkages. More interestingly, the MWCNTs provided a matrix that facilitated the crystallization of CS. Compared with the pure CS, the tensile strength and Young's modulus of the nanocomposites were enhanced significantly from 39.6 to 105.6 MPa and from 2.01 to 4.22 GPa with an increase in the MWCNT loading level from 0 to 3.0 wt %, respectively. The improvement in the tensile strength and modulus were ascribed to the uniform dispersion of MWCNTs covalently linked to the CS matrix. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci: 113: 466-472, 2009