Restenosis after percutaneous transluminal coronary angioplasty (PTCA) is one of the biggest problems in the treatment of coronary artery disease. Although many studies have been performed on lesion-related factors, they are influenced by patient-related factors such as smoking, hyperlipidemia, and the presence of acute coronary syndrome. In this study, lesion-related factors were assessed in the absence of other factors by univariate and multivariate analysis. One hundred and nine lesions were reviewed in 37 consecutive patients with both restenotic lesion(s) and non-restenotic one(s) confirmed by coronary arteriography performed 4.4 +/- 2.2 months after PTCA. Angiographic findings before and immediately after angioplasty were compared between restenotic and non-restenotic lesions. The overall lesion-restenosis rate was 42%. Univariate analysis revealed that calcified lesions (p < 0.05), multiple irregularities (p < 0.01) before angioplasty, residual percentage stenosis (p < 0.05), and angiographical intraluminal haziness (p < 0.05) were related to restenosis. Intimal dissection after PTCA was not associated with restenosis. Multivariate analysis with multiple logistic regression revealed that multiple irregularities (t = 2.8) was the most predictive of restenosis before PTCA and residual percent stenosis (t = 2.6) after the procedure. Coronary lesions with calcification or multiple irregularities indicate high risk of restenosis after PTCA. Optimal dilatation of the lesions without intraluminal haziness regardless of intimal dissection is important to prevent restenosis.