The effect of low-volume fractions of nanoparticles on the morphological processes and the rheological properties of immiscible blends are dis cussed. For blends of poly-isobutylene and poly-dimethylsiloxane stabilized by silica particles, particles help to suppress coalescence. Yet, particle bridging of different droplets has also been reported and leads to a slow build up of a gel-like structure, which could interfere with the morphology evolution under flow. We first investigated the importance of this effect under relevant conditions. To further assess the relative importance of the different processes in technically relevant polymer-polymer blends, the effect of carbon black particles on morphological processes-coalescence and break-up-in polyamide and ethylene-ethylene-metylacrylate copolymers will be studied using rheological methods. It will be shown that particles affect coalescence and break-up, suggesting that the effect of particles is linked to their effect on interfacial dynamics.