In this paper we present a simple one-dimensional model to examine the interplay between dynamic uplift and denudation in response to simultaneous surface erosion and lithospheric deformation under the assumption that the surface elevation of a mountain belt is isostatically compensated and the lithosphere undergoes vertically homogeneous deformation. We also discuss the dynamics of isostatically compensated mountain belts in relation to surface erosion, based on a 'Brace-Goetze' lithospheric model consisting of a quartz-dominated crust and an olivine-dominated upper mantle. The mechanical strength of such a lithosphere is governed by a combination of brittle failure and power law or Dorn law creep. Assuming a simple linear dependence of erosion rate on elevation, we find that contrary to previous suggestions, the effect of high denudation rates on the mechanical strength of the lithosphere does not involve significant weakening of the lithosphere. ¿ American Geophysical Union 1994