The dynamic viscoelastic properties of polypropylene (PP)-maleated PP blends in the molten state have been investigated with a dynamic mechanical thermal analyzer (PL-DMTA MKII) at a frequency range (omega) of 0.6 a 10(-1)-3.14 a 10(2) rad s(-1). In the study, the blends were prepared by melt-blending in a twin-screw extruder, using homopolypropylene and an ethylene-propylene copolymer as a matrix, respectively, and PP grafted with maleic anhydride (PP-g-MA) as a second component. It has been found that the data of the blends do not obey the Cox-Merz rule; the plots of log G＇-log G" for the both blends show a composition dependence. It is due to the fact that the two kinds of PP are immiscible with PP-g-MA.