The study evaluated if excellent mixing conditions prevailing in chaotic mixers also promote droplet coalescence in the mixing of immiscible polymers. A combined approach of experiments and simplified modeling was used to understand the effects of the degree of chaotic mixing, shear rate, and viscosity ratio on coalescence rates. It was found experimentally that the extent of coalescence was substantially reduced when the bulk of the fluid in the mixer experienced chaotic mixing. In addition, coalescence was subdued at higher rates of shear and for higher viscosity ratio droplets. Pseudo-steady state droplet size distributions were reached faster with higher droplet volume fractions and for higher viscosity ratio droplets. (c) 2005 American Institute of Chemical Engineers.