To assess the possible progression of coronary artery disease after percutaneous transluminal coronary angioplasty (PTCA) and its relation to risk factors and restenosis, 124 patients who underwent a first successful PTCA were studied. All had routine follow-up angiography 5 to 8 months after PTCA. Restenosis was defined as a 30% decrease in diameter stenosis or a return to >50% stenosis, and progression (in any nondilated site) as a 20% decrease in diameter stenosis, assessed by a videodensitometric computer-assisted technique. Univariate and multivariate analysis with respect to progression was carried out for age, sex, initial unstable angina, previous myocardial infarction, diabetes mellitus, hypertension, hypercholesterolemia (≥6.2 mmol), smoking habits, Jenkins' score, dilated artery and restenosis. Forty-one patients (33%) had restenosis, and 23 (19%) had evidence of progression; 20 (87%) of these latter patients had restenosis and 3 (13%) did not. Univariate correlates of progression were: previous myocardial infarction (p < 0.05), higher Jenkins' score (p < 0.0003) and restenosis (p < 0.0001). Restenosis was the only multivariate correlate (p < 0.00003). Progression at routine angiography after PTCA is not rare, and appears to be related to both the initial extent of coronary artery disease and restenosis. © 1990.