Previously described vimentin monoclonal antibodies recognize other cellular or intermediate filament proteins in addition to vimentin. In contrast the set of murine monoclonal antibodies described here and elicited using porcine vimentin as antigen appear specific for vimentin. All seven antibodies react only with vimentin in "immunoblot" analysis on gel electrophoretically separated polypeptides from total cell extracts. They do not recognize other closely related intermediate filament proteins including desmin and GFA (glial fibrillary acidic protein). Immunofluorescence microscopy on tissue sections shows a positive reaction in connective tissue, endothelial cells, vascular smooth muscle cells and astrocytes. Typical intermediate filament profiles are documented in fibroblasts and in other cultured cells known to contain vimentin. Although all antibodies react with human and porcine vimentin some show species-specific restriction when rat, mouse and chicken vimentin are used. These results, together with different IgG types and certain aspects of the staining patterns, allow a subdivision of the antibodies. The vimentin antibodies described here complete a set of monoclonal antibodies each specific for only one intermediate filament protein type. Their reaction on human material allows their use in pathology to determine the histogenetic origin of neoplasms.