Certain angiographic patterns outlining the morphologic characteristics of vessels and defining the lesion-specific characteristics have recently been shown to greatly influence the likelihood of a successful dilation. In 1988, ACC/AHA Subcommitte on percutaneous transluminal coronary angioplasty proposed the lesion-specific classification as a guide for estimating the likelihood of a successful procedure as well as the the likelihood of developing abrupt vessel closure. To determine the lesion-specific predictors for successful dilation and complications after percutaneous transluminal coronary angioplasty, nine angiographic charateristics of 200 lesions in 164 patients who underwent coronary angiplasty between May, 1983 and September, 1989 were analyzed. 1) Successful dilation, defined as a reduction in stenosis diameter to less than 50% without acute myocardial infarction or emergency coronary artery bypass graft, occurred in 175 of 212 lesions(82.5%). 2) Successful dilation occurred in 13 of 15 type A lesions(86.6%), 148 of 178 type B lesions(83.1%) and 3 of 7 type C lesions(42.8%)(p<0.05 for A or B vs C). 3) Acute closure syndrome occurred in none of type A lesions, 6 of type B lesions(3.4%), 2 of type C lesions(28.5%)(p<0.005 for A or B vs C). 4) multivariate analysis showed that lesion-specific characteristic predictors for successful dilation were length of lesion(p<0.05) and accessibility(p<0.05) ; for ischemic events were major branch involvement(p<0.05) and eccentricity(p<0.05); for acute closure syndrome were accessibility(p<0.05) and eccentricity(p<0.05). 5) Procedural predictors for ischemic events were coronary artery dissection(p<0.01), post-PTCA diameter stenosis(p<0.05) and balloon/artery diameter ratio(p<0.01) ; For acute closure syndrome was coronary artery dissection(p<0.005). In this analysis, we found that angiographic lesion-specific characteristics related very importantly to procedural success and were able to define three major independent lesionspecific risk factors whose presence beforehand decreased the likelihood of successful dilation and increased the likelihood of acute closure. In the absence of any of these risk factors, the risk of acute closure is very small. Thus, identification of these factors and their associate risk should improve patients selection and better define the role of coronary angioplasty in the management fo patients with coronary artery disease.