Nonlinear Alfv¿n waves, in inhomogeneous plasmas, are shown to be governed by the MDNLS (Modified Derivative Nonlinear Schr¿dinger) equation. The inhomogeneity leads to acceleration (deceleration) of the Alfv¿n solitons depending upon plasma &bgr; (kinetic pressure/magnetic pressure) and on density gradients vis-a-vis direction of wave propagation. Potential applications, of the model, to space and astrophysical plasmas are pointed out.