BACKGROUND: Coronary arterigraphy has been used as a tool to assess the degree of coronary artery narrowing and the result of balloon angioplasty, which frequently underestimates the degree of atherosclerosis. Intravascular ultrasound(IVUS) can give more delicate information about plaque morphology and the result of coronary intervention. We compared qualitaive and quantitative measurement between IVUS and coronary angiography after coronary intervention. METHODS: We used 30 or 20 MHz intravascular ultrasound catheter which was connected to Hewlett Packard Sonos 1500 Intravasscular equiment in 5 coronary balloon angiopasty and 3 Palmaz-Schatz stent implantation cases. Sites of intervention were at the left anterior descending coronary artery in 7 patients and at the left circumflex artery in one patient. Quantitative coronary angiography(QCA) was done by CAAS II system. We measured referenc diameter(RD), minimal lumen diamter(MLD), Lumen and vessel cross sectional areas(LCSA,VCSA) obstraction area(OA) and plaque area(PA) and also analysed plaque morphology. RESULTS: 1) IVUS is more sensitive in the detection of eccentricity, Calcification and dissection. 2) Before intervention, the mean reference diameter was 2.87+/-0.42mm,3.07+/-0.39mm,% diameter stenosis was 52.4+/-11.6%,65.3+/-9.22% and MLD was 1.32+/-0.24mm, 1.07+/-0.23mm in IVUS and QCA, respectively, which were no statistical significance between these parameters(p>0.05). After intervention, MLD and OA increased significantly(p<0.01) com pared with basal values but there were no significant difference between MLD and OA between 2 measurements(p>0.05). Plaque area measured by IVUS decreased from 9.84 to 7.26mm2 without statistical significance(p>0.05). 3) There was a good correlation in the measurement of the reference segments before intervention but this correlation was much lower after intervention in the reference and stenosis segments between 2 methods(r=0.8723 vs 0.6538, p<0.01). CONCLUSION: IVUS is considered as a sensitive tool in the detection of calcification, eccentricity and dissection and in evaluationg the results of the coronary intervention.