The crystallization and melting behaviors of maleated polyethylene (MPE) and its composite with fibrous crystalline cellulose are investigated by differential scanning calorimetry. MPE exhibits a higher crystallization starting temperature, because of the interactions between maleic anhydride (MA) groups for nucleation, and lower melting and crystallization enthalpies, because of the intensive irregularity of MPE chains compared to unmaleated PE (UPE). Fibrous cellulose (FC) slightly facilitates the nucleation of MPE but causes no change in the transition enthalpies of MPE for crystallization and melting in UPE-FC and MPE-FC composites. The kinetics of crystallization show that the Avrami exponent depends on the content of MA groups and FC to a small extent and the activation energy is largely determined by the MA content, suggesting the irregularity and decreased mobility of MPE chains that is due to the interactions between the grafted MA groups in MPE and the FC composite. (C) 2003 Wiley Periodicals, Inc.