The deformation of carbon nanotube (CNT)-filled PA6 droplets in PP matrix was examined under simple shear flows. The morphology of blends with various CNT contents in PA6 were probed by FE-SEM. Based on the wetting coefficient calculations and rheological measurements, it was noted that the majority of CNTs were selectively located in the PA6 phase for concentrations up to 2 wt%. TEM micrographs evidenced the results for a sample with 0.5 wt% CNT in PA6. Optical microscopy of the blends during simple shear flows revealed the reduced deformability and breakups for filled-droplets. Such observations were ascribed to the increased viscosity ratio and gradual formation of an elastic structure within the droplets. Maffetone-Minale transient droplet deformation model was coupled with a modified capillary number to account for the developed elastic forces. It was shown that the contribution of such forces to the total shape-conserving forces could arise up to 99% in comparison with the well-known interfacial forces. These resisting forces can be so strong that for blends with CNT concentrations above 0.5 wt% in PA6 almost no deformation was observed under the applied shear stresses in this work. POLYM. ENG. SCI., 55:1504-1519, 2015. (c) 2014 Society of Plastics Engineers