Balloon angioplasty of a bifurcation lesion is associated with lower rates of success and higher rates of complications than such treatment of lesions of most other morphologies. To date, the best device or procedure for bifurcation lesions has not been determined. The aim of this study was to compare the immediate and 3-month follow-up outcome of cutting balloon angioplasty (CBA) versus conventional balloon angioplasty (PTCA) for the treatment of bifurcation lesions. We treated 87 consecutive bifurcation lesions with CBA (n = 50) or PTCA (n = 37). Paired angiograms were analyzed by quantitative angiography, and angiographic follow-up was achieved for 93% of the lesions. The procedural success was 92% in the CBA group and 76% in the PTCA group (P < 0.05). Major in-hospital complications occurred in two lesions in the CBA group and six in the PTCA group (P = 0.05). The incidence of bail-out stenting in the CBA group was lower than in the conventional PTCA (8% vs 24%, P < 0.05). At the 3-month follow-up, the restenosis rate was 40% in the CBA group versus 67% in the PTCA group (P < 0.05). Clinical events during follow-up did not differ between the two groups. In conclusion, in comparison with PTCA, procedural success was greater and the restenosis rate lower with CBA. The results of this study support the use of the cutting balloon as optimal treatment for bifurcation lesions.