Previous studies have shown a high rate of repeat intervention after treating diffuse in-stent restenosis with percutaneous transluminal coronary angioplasty (PTCA) alone. It is not clear whether debulking with atherectomy is more effective in this condition. Between January 1994 and February 1997, we treated 60 consecutive patients with diffuse in-stent restenosis of a native coronary artery using conventional PTCA (n=30) or debulking (with rotational or directional atherectomy) plus adjunctive PTCA (n=30). Paired angiograms were analyzed by quantitative angiography, and clinical follow-up was obtained in all patients at 1 month, 6 months, and 1 year after revascularization. The mean lesion lengths were 13.5+/-8.3 and 18.4+/-13.2 mm in the debulking and PTCA groups, respectively (p=0.09). Acute procedural success was 100% in both cohorts, with no major complications in either group. Treatment with atherectomy plus adjunctive PTCA resulted in lower postprocedure stenoses (18+/-10 vs 26+/-13%, p=0.01) than treatment with balloon angioplasty alone. At 1-year follow-up, repeat target vessel revascularization was required in 28% of patients in the debulking group compared with 46% in the PTCA group (p=0.18). Independent predictors of the need for repeat target vessel revascularization were longer lesion lengths, diabetes mellitus, and smaller postprocedure lumen diameter. Thus, the strategy of atherectomy and adjunctive PTCA for diffuse in-stent restenosis is safe, improves acute angiographic results compared with PTCA alone, and may decrease the need for target vessel revascularization.