The effects of carbon nanotubes (CNT) on the morphology, mechanical and electrical properties of immiscible polypropylene/polyethylene (PP/PE) blends were investigated. PP/PE (90/10) blend filled with up to 20 wt% CNT and PP/PE blends with different PP/PE volume ratios and constant CNT volume fraction were prepared by melt mixing. The morphology analysis showed that the nanotubes have higher affinity towards the PE phase. However, for the 90/10 PP/PE blend filled with 20 wt% CNT, some nanotubes were observed within the PP phase due to the saturation of the PE minor phase. The 90/10 PP/PE blend exhibited co-continuous morphology even at very low CNT content because of the low interfacial tension between PE and PP (gamma (PE-PP) = 0.8-1.2 mN/m). Remarkable enhancement in tensile strength was obtained with the increase in nanotubes concentration. The blend's electrical percolation threshold concentration was found to be in the range of 1-1.5 wt% CNT, which is lower than that of the CNT/PE nanocomposite.