Background The effectiveness of sustained-release basic fibroblast growth factor (bFGF) in potentiating arteriogenesis and angiogenesis was evaluated, as well as determining whether chronic oral administration of sarpogrelate, a serotonin blocker, would further increase collateral blood flow in the rabbit hindlimb following surgical induction of ischemia by femoral artery extraction. Methods and Results Two weeks after femoral artery removal, the rabbits were assigned to 1 of 4 experimental groups and treated for 4 weeks: group A, no treatment; group B, supplemented with diet containing sarpogrelate; group C, single intramuscular injection of sustained-release form of bFGF microspheres; group D: combined treatment with sustained-release bFGF and sarpogrelate. Endpoint measurements performed at 6 weeks found that the ischemic hindlimb blood flow was significantly improved in the rabbits that received sustained-release bFGF, with a further significant improvement in those with the additional administration of sarpogrelate. Angiographic assessment revealed augmented density of collateral vessels in the medial thigh region in the rabbits given the combined treatment. Conclusions The findings demonstrate that sustained-release bFGF stimulated the development of collateral vessels, and additional administration of sarpogrelate produced a further improvement in hindlimb blood flow in the rabbit hindlimb ischemia model. (Circ J 2006; 70: 1190 - 1194)