Objectives: Coronary flow reserve(CFR) is the ratio of the maximal hyperemic to basal coronary blood flow velocity hyperemia, which was introduced by Gould et al, as a functional parameter in the coronary artery stenosis. Methods: To evaluate the difference of the CFR between the significant and insignificant coronary artery narrowings, we measured coronary flow velocity in 17 patients(11 nonstenotic group and 6 stenotic patients) by 0.0l4 inch intracoronary Doppler-tipped guidewire after nitroglycerine 200㎍ intracoronary infusion during coronary arteriography. We measured coronary flow velocity in 11 left coronary artery and 6 right coronary artery before and after adenosine intracoronary infusion(LCA 12㎍, RCA 6㎍). Results: 1) Average peak velocity(APV, cm/sec) of steno- tic patients was higher than nonstenotic group(19.8 vs 36.6, p<0.05), but diastolic systolic velocity ratio (DSVR) were not significantly different between both groups. 2) APV after adenosine infusion in stenotic and nonstenotic group were 56.3±16.4, 60±23.4cm/sec, respectively, which are significantly increased compared to the basal state(p<0.01). 3) Mean coronary flow reserve(CFR) in the stenotic group was significantly lower than nonstenotic group(1.98±0.9 vs 3.57±1.0, p<0.01). 4) Systolic and diastolic blood pressure decreased significantly after adenosine intracoronery bolus infusion(p<0.01), but heart rate did not changed significantly(p>0.05). The mean time that came back to the baseline flow velocity after adenosine infusion was 27.1 seconds. Conclusion: Coronary flow reserve decreased significantly in the coronary artery stenosis compared to normal or insignificant stenosis. And adenosine caused significant fall in blood pressure after intracoronary infusion, but did not in heart rate