A common method to achieve a contact of two liquid phases-required for many chemical engineering operations-is the dispersion of one into the other by mechanical agitation. The drop size distribution in such an agitated dispersion is a result of the dynamic equilibrium existing between the breaking and coalescing drops. A comparison has been made of drop diameters produced by four disk type impellers differing only in blade height (D-W = 1, 2, 4 and 6 cm). Measurements in situ at 200, 250, 300, 350 400 450 rpm and at holdup fractions 0.02, 0.05, and 0.07, showed that the Sauter mean drop diameters increased up to 140% as the impeller blade height decreased from 6 to 1 cm. Plots of In a(32) vs. In N, Ina(32) VS- In D-T and In a(32) vs. In a(max) gave straight lines.