The aim of this study is to investigate the effects of onion vinegar on the cerebral blood flow by measuring the changes of regional cerebral blood flow (rCBF) and mean arterial blood pressure (MABP) and by observing the recovery of focal ischemic brain injury in rats. Rats are divided into thee groups depending on the medication; control group (no medication), 8.8-OV group (vinegar using 8.8 brix onion medication), 14.6-OV group (vinegar using 14.6 brix onion medication). The medication of onion vinegar significantly increased rCBF but decreased MABP. This result suggests that onion vinegar significantly increased rCBF by dilating arterial diameter. In addition, focal ischemic brain injury is induced in rats by middle cerebral arterial occlusion. The recovery from focal ischemic brain injury is more significantly improved in the groups using onion vinegar compared to the control group. The amount of recovery is measured by the GAP-43 and the medication of onion vinegar significantly increased GAP-43. This result suggests that onion vinegar is effective on the nerve regeneration. After the medication, the change of body weight, outcomes of renal and liver function test, and outcomes of CBC are analysed for safety examination. There are no statistical differences among control group and all experimental groups in the body weight, renal and liver function test, and CBC. In conclusion, these results suggest that onion vinegar can increase rCBF in normal state, and improve the stability of rCBF in ischemic state.