The purpose of this study is to measure the changes of regional cerebral blood flow (rCBF) and blood pressure (BP) in rats, following the intravenous injection of Catalpa Ovata Water Extract (COWE). The measurement was continually monitored by laser-doppler flowmeter (Transonic Instrument, USA) and pressure tranducer(Grass, USA) in anesthetized adult Sprague-Dawley rats through the data acquisition system composed of MacLab and Macintosh computer. The result of this experiment was as following : COWE increased the changes of rCBF and BP significantly. After pretreatment with propranolol and indomethacin, the changes of rCBF were inhibited significantly, but not by L-NNA and methylene blue. Also, after pretreatment with propranolol, the changes of BP were inhibited significantly, but not by L-NNA, methylene blue and indomethacin. According to above result, it is considered that Catalpa Ovata increased the rCBF and BP, related to adrenergic β-receptor.