Abstract Enucleation of cultured human fibroblasts was used to study the interaction between the nucleus and the cytoskeletal intermediate filaments. In enucleated cells the filaments stained for immuno-fluorescence were seen as fibrillar cytoplasmic arrays similar to those of intact cells. Typical reorganization of the filaments into coiling bundles occurred in cells treated with vinblastine either before or after enucleation. The cytoplasmic stalk connecting the extruding nucleus to the rest of the cell contained filaments, whereas the karyoplasts lacked them. The present results indicate that the filaments are essential for the anchorage of the nucleus and that the weakest point in this system is between the nucleus and the intermediate filaments.