Randomized clinical trials have shown that paclitaxel-eluting stents significantly reduce restenosis after percutaneous coronary intervention. The impact of lesion calcification on the efficacy of paclitaxel-eluting stents is unknown. In the TAXUS-IV trial, 1,314 patients who underwent percutaneous coronary intervention were randomly assigned to a bare-metal or paclitaxel-eluting stent. By core laboratory analysis, 247 lesions (19%) were moderately or severely calcified. At the 9-month angiographic follow-up examination, the paclitaxel-eluting stent had significantly reduced the amount of late loss compared with the control stent (0.26 +/- 0.56 vs 0.51 +/- 0.48 mm, p = 0.015) within the analysis segment in the calcific lesions. The analysis segment restenosis rate was similar in patients with calcified and noncalcified lesions after paclitaxel-eluting stent implantation (7.5% vs 8.0%, respectively; p = 1.0). The rate of ischemia-driven target lesion revascularization (TLR) at 1 year was reduced by 56% in patients with calcified lesions (11.9% vs 5.1%, p = 0.09) and by 75% in noncalcified lesions (15.7% vs 4.3%, p <0.0001). By interaction testing, the efficacy of the paclitaxel-eluting stent in reducing TLR at 1 year was similar in the calcified and noncalcified lesions (p = 0.30). Moreover, by multivariate analysis, implantation of the paclitaxel-eluting stent was a powerful independent predictor of freedom from TLR, with similar hazard ratios for efficacy in calcified and noncalcified lesions (0.30 and 0.26, respectively). In conclusion, implantation of paclitaxel-eluting stents in patients with de novo coronary lesions significantly reduced restenosis in patients with and without calcified lesions.