Between March 1991 and June 1994, the authors treated restenosis (> or = 50%) of coronary endoprostheses in 17 men aged 39 to 72 years by balloon angioplasty. The stents had been implanted for de novo stenosis in 14 patients, restenosis in 1 patient and for acute occlusion in 2 patients. The vessels treated were the left anterior descending artery (1 case), the left circumflex artery (2 cases), the right coronary artery (7 cases) and venous bypass grafts (7 cases). The endoprostheses used were 5 Wallstents in 4 patients, 13 Wiktor stents in 11 patients and 2 Palmaz-Schatz in 2 patients. Clinically, the patients with restenosis presented with class II angina (6 patients), class III (8 patients) and class IV (3 patients) of the Canadian Cardiovascular Society Classification. Conventional balloon angioplasty was performed 17 months (range: 3 to 87 months) after stent implantation and resulted in immediate clinical and angiographic success (residual stenosis < or = 50% on quantitative analysis) in all patients. In particular, there were no dissections. The minimal lumenal diameter (MLD) and percentage stenosis changed from 1.04 mm (range: 0.87 to 1.20) and 72% (range: 68 to 76) respectively before stent implantation to 2.83 mm (range: 2.46 to 3.20) and 23% (range: 20 to 27) after stent implantation. Restenosis resulted in a MLD and percentage stenosis of 0.89 mm (range: 0.77 to 1.01) and 73% (range: 69 to 78) respectively. After angioplasty of the stent, they returned to 2.68 mm (range: 2.29 to 3.06) and 27% (range: 23 to 30) respectively. The patients were not anticoagulated after angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)