Mutations in the lamin A gene have been shown, among other defects, to give rise to Hutchinson-Gilford progeria syndrome (HGPS) and to atypical Werner syndrome (WS), both of which are progeroid disorders. Here, we have investigated well-characterized WS patient cell strains that are compound heterozygous for mutations in the WRN gene. As in HGPS and in atypical WS, we found nuclear deformations to be characteristic of all cell strains studied. In WS cells centrosome number, assembly of the nuclear lamina and nuclear pore distribution occurred normally. Furthermore, nuclear deformations were not associated with a defect in lamin A expression. We propose that nuclear deformation is a universal characteristic of progeroid cells and may result from slow cell cycle progression.