Recently, much attention has been paid to the arterial gene transfer technique using several vector systems. In the present study, we experimentally examined the transfection efficiency of the exogenous gene, the duration of gene expression, and the cytotoxic effect of the hemagglutinating virus of Japan (HVJ) liposome on the intact arterial wall to evaluate its effectiveness for the study of arterial diseases. To evaluate the transfection efficiency and duration of gene expression, pSV beta-galactosidase was transferred into the carotid arterial wall of rabbits. The cytotoxic effect of HVJ liposomes on the vascular cell components was also evaluated by a neutral red assay in vitro and scanning electron microscopy in vivo. HVJ liposomes could achieve highly efficient gene transfection into the medial smooth muscle cells of intact arteries at 150 and 760 mmHg of pressure (mean = 85.3% and 93.5% of total smooth muscle cells, respectively) without any inflammatory reaction. The introduced exogenous gene was expressed for at least 14 days. In addition, the cytotoxicity for the arterial smooth muscle cells and endothelial cells induced by HVJ liposome vehicles at routinely used concentrations (5,000 to 10,000 hemagglutinating activity units/ml) was minimal both in vitro and in vivo. As an example, we introduced human vascular endothelial growth factor cDNA, which was driven with cytomegalovirus enhancer and beta-actin promoter, into the rabbit carotid arteries, and it induced not only angiomatoid proliferation of endothelial cells forming irregular vascular channels but also intimal hyperplasia. Based on these findings, we conclude that HVJ liposome-mediated arterial gene transfer is a highly efficient, noninvasive, and effective gene delivery method for the study of vascular disorders.