The rheological behavior of clay suspensions, oil-in-water emulsions, and their blends was investigated using a controlled-stress rheometer. The suspensions exhibited Newtonian behavior at low solids volume fractions; at high solids concentrations, a shear-thinning behavior was observed. The emulsions of kerosene in water were shear-thinning over the oil volume fraction range of 0.171-0.637. The blends of suspensions and emulsions (keeping the volume fraction of the dispersed phase constant) exhibited strong synergistic effects at low to moderate values of shear stress due to interactions between the clay particles and oil droplets. The blend viscosity exhibited a minimum at an emulsion proportion of about 30-40 vol %. The high shear viscosity data of blends of suspensions and emulsions were successfully correlated in terms of the viscosity ratio versus volume fraction of solids, where viscosity ratio was defined as the ratio of blend viscosity to pure emulsion viscosity.