We used a monoclonal antibody specific for vimentin from human fibroblasts to stain whole mounts of Drosophila embryos. In immunofluorescence observations this antibody cross-reacts with an antigenic determinant localized throughout mitosis at the nuclear boundary. Double fluorescence observations with the Rb188 antibody that specifically recognizes a centrosomal protein of the Drosophila embryo [Whitfield et al., 1988] showed that the anti-vimentin antibody cross-reacts with an antigen localized in the centrosomal region.