We consider the influence of a 15 km thick ductile crustal layer of viscosity 1018 Pa s embedded in an elastic 80 km lithosphere on predictions of ongoing glacial isostatic adjustment (henceforth 'GIA') along the U.S. east coast. Crustal velocities are perturbed by 0.5 mm/yr, or more, by the inclusion of the ductile layer. Furthermore, perturbations in predictions of sea-level rates along the U.S. east coast due to the ductile layer have a geographic pattern that is similar to residual trends evident in previous GIA corrections of tide gauge records along this coast. ¿ 2000 American Geophysical Union