The cutting balloon (CB) is a specialized device designed to create discrete longitudinal incisions in the atherosclerotic target coronary segment during balloon inflation. Such controlled dilatation theoretically reduces the force needed to dilate an obstructive lesion compared with standard percutaneous transluminal coronary angioplasty (PTCA). We report a multicenter, randomized trial comparing the incidence of restenosis after CB angioplasty versus conventional balloon angioplasty in 1,238 patients. Six hundred seventeen patients were randomized to CB treatment, and 621 to PTCA. The mean reference vessel diameter was 2.86 +/- 0.49 mm, mean lesion length 8.9 +/- 4.3 mm, and prevalence of diabetes mellitus in patients was 13%. The primary end point, the 6-month binary angiographic restenosis rate, was 31.4% for CB and 30.4% for PTCA (p = 0.75). Acute procedural success, defined as the attainment of <50% diameter stenosis without in-hospital major adverse cardiac events, was 92.9% for CB and 94.7% for PTCA (p = 0.24). Freedom from target vessel revascularization was slightly higher in the CB arm (88.5% vs 84.6%, log-rank p = 0.04). Five coronary perforations occurred in the CB arm only (0.8% vs 0%, p = 0.03). At 270 days, rates of myocardial infarction, death, and total major adverse cardiac events for CB and PTCA were 4.7% versus 2.4% (p = 0.03), 1.3% versus 0.3% (p = 0.06), and 13.6% versus 15.1% (p = 0.34), respectively. In summary, the proposed mechanism of controlled dilatation did not reduce the rate of angiographic restenosis for the CB compared with conventional balloon angioplasty. CB angioplasty should be reserved for difficult lesions in which controlled dilatation is believed to provide a better acute result compared with balloon angioplasty alone.