We evaluated the effect of basic fibroblast growth factor (bFGF) on the extent of atherosclerosis and balloon injury-induced vasoproliferation in atherosclerotic animals with acute myocardial infarction (AMI). Fifty-six rabbits were fed a 1% cholesterol diet. Balloon injury of iliac arteries and experimental acute myocardial infarction were induced in the same animals. Rabbits were then randomized to a bFGF group (20 pg/day, intravenously) or a control group (intravenous saline solution). The beneficial effects of bFGF on cardiac function, infarct size, and collateral vessel development, and the possible effect on vasoproliferation of balloon-injured vessels, were measured after 1 and 2 weeks. The extent of atherosclerosis was measured after 1, 2, and 4 weeks. Our results showed that bFGF significantly reduced infarct size and increased collateral-vessel density (P <.01) in infarct areas. Cardiac function was better in the bFGF group than in corresponding controls (P <.05). Similar beneficial effects of bFGF were noted in animals after 1- and 2-week treatments. However, the extent of atherosclerosis and the vasoproliferation in chronic atherosclerotic vessels induced by balloon injury and cholesterol diet were not significantly different between the two groups. Our results suggest that short-term treatment with bFGF enhances collateral development and produces maximum therapeutic benefits without exacerbating atherosclerosis and cell proliferation in stenotic vessels after AMI in atherosclerotic rabbits.