Morphological investigation was carried out with melt-mixed ternary polymer blends of polyamide6 (PA6), polypropylene (PP) and acrylonitrile butadiene styrene copolymer (ABS) in the presence of compatibilizer and multiwall carbon nanotubes (MWNTs). 80/10/10 (wt/wt/wt) PA6/PP/ABS and 80/10/10 (wt/wt/wt) PP/PA6/ABS blends exhibited ''core-shell'' morphology, whereas 80/10/10 (wt/wt/wt) ABS/PP/PA6 blends exhibited ''separately dispersed'' phase morphology. The type of phase morphology was unaltered in the presence of either compatibilizer or MWNTs in the respective ternary polymer blends. The morphological refinement in the presence of compatibilizer was explained on the basis of melt-interfacial reaction. In contrast, the refinement in the dispersed droplets in the presence of MWNTs was due to the localization of MWNTs in the specific phase. Dynamic relaxation spectroscopic analysis indicated an increase in the relaxation time of PA6 chain in the presence of compatibilizer in the corresponding ternary blends. The variation in the relaxation time was dependent on the efficiency of the compatibilizer. The variation in the relaxation time for PA6 in the presence of 1 wt% MWNTs in the respective ternary blends also followed a similar trend; however, the extent of mobility of PA6 phase was influenced by the state of dispersion of MWNTs in the corresponding blends.