Percutaneous transluminal balloon coronary angioplasty (PTCA) of coronary bifurcations is associated with a low success rate, high rate of complications, and high incidence of target vessel revascularization (TVR). The strategy of systematic coronary stenting in bifurcation lesions involving a side branch >/= 2.2 mm in diameter was prospectively evaluated in a single-center observational study during a 35-month inclusion period. All patients meeting these criteria were consecutively included. Bifurcation lesions and treatment were predefined in the study. The study included 366 patients (12.1% of PTCA) with 373 bifurcation lesions, mean age 63.7 +/- 11.6 years, 79.2% male, 46.7% with unstable angina, and 8.3% acute MI. The left anterior descending/diagonal bifurcation was involved in 55.2% of cases, circumflex/marginal 22. 2%, PDA/PLA 10.4%, left main bifurcation in 6.8%, and others 5.4%. The main branch (2.78 +/- 0.42 mm reference diameter) was stented in 96.3% of cases and the side branch (2.44 +/- 0.43 mm) in 63.2% (the two branches were stented in 59.5% of cases). Procedural success was obtained in 96.3% in both branches and 99.4% in the main branch. At1-month follow-up, The major cardiac event rate (MACE) was 4.8% (death 1.1%, emergency CABG 0.6%, Q-wave MI 0.9%, acute or subacute closure 1.4%, repeat PTCA 1.1%, and non-Q-wave MI 2.3%). At 7-month follow-up, the total MACCE rate was 21.6%, including a TVR rate of 17.2%. Analysis of the 7-month outcome according to two study periods (period I, 1 January 1996 to 31 August 1997, 182 patients; period II, 1 September 1997 to 30 June 1998, 127 patients) showed that the TVR rate decreased from 20.6% to 13.8% (P = 0.04) and the MACE rate from 29.2% to 17.1% (P < 0.01) in period I and II, respectively. This was associated by univariate analysis with an increasing use of tubular stents deployed in the main branch (94.2% vs. 59.1%, P < 0.001) and kissing balloon inflation after coronary stenting (75.4% vs. 18.1%, P < 0.001). Bifurcation lesions are frequent. Procedural success of coronary stenting is high with a low rate of in-hospital MACE. TVR rate at follow-up is relatively low. In-hospital and follow-up results are influenced not only by the learning curve but also by the use of tubular stents in the main branch and final kissing balloon inflation.