The phase separation of mixtures of four-armed star polystyrene with linear polyvinyl methyl ether) was investigated by time-resolved light scattering. It was found that the kinetics of phase separation was essentially the same as that of the corresponding mixtures of linear polymers. The effect of chain topology was evident only when the molecular weights of the individual arms were large. This resulted in a reduced rate of phase separation. The linearized Cahn-Hilliard-Cook theory of spinodal phase separation qualitatively described the features of the experiments; however, the scattering vector dependence of the amplification factor deviated from the expected behavior. © 1990, American Chemical Society. All rights reserved.