Vascular smooth muscle cell (VSMC) proliferation associated with arterial injury causes restenosis, which remains to be resolved in cardiovascular and ischemic cerebrovascular disease, especially after balloon angioplasty. Fibroblast growth factor (FGF) is a potent mitogen and a trophic factor for a variety of cells, including VSMCs. We constructed a replication-deficient adenovirus vector, designated AxCA delta FR, coding a truncated form of fibroblast growth factor receptor-1 (FGFR-1) gene lacking the intracellular domain to interrupt receptor-mediated FGF signaling, and examined its effect on the proliferation of primary-cultured rat VSMCs. We transferred the truncated form of the FGFR-1 gene to the VSMCs and confirmed its expression and localization in infected cells by Western blotting and immunofluorescence study. The VSMCs infected with AxCA delta FR degenerated and the proliferation of these cells was suppressed markedly by the infection with this virus in vitro. Our results suggest that the receptor-mediated signal of FGFs has an important role in VSMC proliferation and gene transfer of a truncated form of FGFR using adenoviral vector may be useful for the treatment of the diseases caused by excessive proliferation of VSMCs like restenosis after percutaneous transluminal angioplasty or carotid endoarterectomy.