After percutaneous transluminal coronary angioplasty (PTCA), 30–50% of the patients may present with restenosis within 6 months. The aim of this study was to search for a preventive remedy against the balloon injury-induced neointima formation. Ginseng, with its wide indications on immune and cardiovascular functions, has prompted us to explore its role in neointima formation. In the present study, we aimed to explore if a standardized Panax Ginseng extract G115 was able to inhibit neointimal formation. With BrdU luminencence assay, maximal proliferation of rat smooth muscle cells was reduced to 24% of control values by G115. Norepinephrine-induced vasocontraction was antagonized in 21% and 44% by 1.44mg/ml and 2.88mg/ml of G115, respectively. Neointima-to-lumen area ratio of balloon-injured rat carotid arteries was reduced 77.3% by G115 as compared to the sham control. These results demonstrate the preventive effects of ginsenosides on angioplasty-mediated neointima formation.