The possible expression of fibroblast growth factor in cultured bovine vascular smooth muscle (VSM) cells derived from bovine adult aortic arch has been examined. VSM cells were found to express the basic fibroblast growth factor (bFGF) gene but not that of acidic fibroblast growth factor (aFGF), a related mitogen. Expression of bFGF was further examined. VSM cells contain 3.7 and 7.0 kilobase bFGF gene transcripts, which are translated into material closely related, if not identical, with bFGF when analyzed by its chromatographic behavior on heparin Sepharose, by immunoblot and by radioimmuno- and radioreceptor assays. Essentially all of the bFGF-like material is bioactive, i.e., it can stimulate the proliferation of capillary endothelial or VSM cells and the stimulation is blocked by anti-bFGF antibodies. Our results indicate that bFGF derived from VSM cells may act as a paracrine and autocrine growth factor for that cell type. Thus, bFGF could play an important role in vivo, in controlling the proliferation of VSM cells during embryonic growth of blood vessels or during atherosclerosis.