We propose and demonstrate a new computational approach which enables the simulation of the dynamics and rheology in inhomogeneous phases of multicomponent polymeric systems. Our approach generalizes Doi's dynamical mean-field theory of rodlike polymers by combining single chain Brownian dynamics algorithms with phenomenological prescriptions for the dynamics of coarse-grained field variables. We provide a general overview of the technique and illustrate its applicability by our results in the context of a symmetric A+B polymer blend. (C) 2003 American Institute of Physics.