ChongMyeong-Tang(CMT) have been used clinically to treat patient with amnesia and dementia. In addition, CMT have been also used for examinee to improve learning ability in Korea. This experimental study was designed to investigate the effects of Gagam-ChongMeong-Tang(GCMT) to improve the retentive faculty and learning ability in terms of Cerebral blood flow(rCBF) and Mean Artery Blood Pressure(MABP) in rats. In our study, we investigated that increasing doses of GCMT (1 ug/ml, 10 ug/ml, 100 ug/ml, and 1000 ug/ml) affect the level of rCBF and MABP in rats. In our results, treatment with GCMT elevated level of rCBF in dose dependant manner. Cantraray, level of MABP was lowered by treatment with GCMT. The involved mechanisms in rCBF are guanylate cyclase pathway. During the period of cerebral re-perfusion, GCMT treated group showed stability of rCBF compared to control group. These results imply that GCMT increased rCBF through dilation of pial artery. And related mechanisms are involved in guanylate cyclase pathway.