Experimental investigation was conducted on a liquid-liquid dispersion in a stirred vessel in which the effects of dispersed phase viscosity were studied. Different grades of silicone oils were used to create oil-in-water dispersion by using Rushton turbine as an impeller, and drop sizes were measured by laser diffraction technique. Dispersion with higher uniformity of drop sizes was produced at low viscosity and high impeller speed. The dispersed phase viscosity influenced the equilibrium Sauter mean diameter, d(32) by contributing to drops stabilization. The decrement of d(32) with an increase in impeller speed is larger for high dispersed phase viscosities. It shows the influence of number and size of drop fragments formed after drop breakup on the mean drop size. Correlations relating d(32) and dispersed phase viscosity were proposed with an accuracy of more than 90% between the predicted and experimental values.