B ecause fibroblast growth factors (FGFs) modulate important functions of endothelial cells (EC) and smooth muscle cells (SMC), we studied FGF expression in human vascular cells and control or atherosclerotic arteries. All cells and arteries contained acidic (a) FGF and basic (b) FGF mRNA. Northern analysis detected aFGF mRNA only in one of five control arteries but in all five atheroma tested, while levels of bFGF mRNA did not differ among control (n = 3) vs. plaque specimens (n = 6). Immunolocalization revealed abundant bFGF protein in control vessels (n = 10), but little in plaques (n = 14). In contrast, atheroma (n = 14), but not control arteries (n = 10), consistently exhibited immunoreactive aFGF, notably in neovascularized and macrophage-rich regions of plaque. Because macrophages colocalized with aFGF, we tested human monocytoid THP-1 cells and demonstrated accumulation of aFGF mRNA during PMA-induced differentiation. We also examined the expression of mRNA encoding FGF receptors (FGFRs). All cells and arteries contained FGFR-1 mRNA. Only SMC and control vessels had FGFR-2 mRNA, while EC and some arteries contained FGFR-4 mRNA. The relative lack of bFGF in plaques vs. normal arteries suggests that this growth factor may not contribute to cell proliferation in advanced atherosclerosis. However, aFGF produced by plaque macrophages may stimulate the growth of microvessels during human atherogenesis.