The dielectric constant epsilon’ of emulsions undergoing a steady shear flow was measured on a series of systems in which ca. 10 wt % of poly(propylene oxide) (PPO) was suspended in poly(dimethylsiloxane) (PDMS) of different viscosity. The data obtained by such a rheodielectric study indicated that epsilon’ decreases with increasing shear rate gamma, reflecting elongation and orientation of initially spherical PPO droplets in the flow direction. Based on Sillars’ theory, we determined from the decrement Delta epsilon of the dielectric constant the degree of deformation D = (X - Y)/(X + Y) of the ellipsoidal droplet, where X and Y are the lengths of the major and minor axes, respectively. The gamma dependence of D depended strongly on the viscosity ratio lambda (=eta(1)/eta 2) of the droplet eta(1) to the matrix eta(2). When lambda was smaller than 1, D increased almost linearly with gamma, while lambda greater than or similar to 8, D quickly leveled off and became independent of gamma for gamma > 5. The behavior was explained semiquantitatively by the theory of Torza, Cox, and Mason.