As a study on the extraction apparatus for separation and purification of proteins and other molecules using reversed micellar systems, the mean drop diameter and drop size distribution of the reversed micellar dispersed phase have been investigated using a rotating disc contactor (RDC) of 38 mm diameter. The Sauter mean diameter was correlated with the Reynolds number, Re, the Weber number. We and the density ratio of the two phases, and the correlation was found to be in good agreement with the experimental data within 15%, The data obtained from the experimental runs and the correlation are compared with those of other authors for liquid-liquid systems without surfactants. The Mugele-Evans distribution function has proved to be the best of the four functions of Mugele-Evans, log-normal, normal and Weibull distribution functions for representing the experimental drop size distribution data. Correlations for the distribution function parameters by means of the Sauter mean diameter obtained in this work can be used to estimate drop size distribution of the reversed micellar systems.