BACKGROUND AND OBJECTIVES: revious studies have shown a high restenosis rate after balloon angioplasty for diffuse in-stent restenosis. Debulking strategy has been expected to be helpful to reduce the restenosis rate. This study evaluated the safety and long-term clinical event rate after excimer laser coronary angioplasty (ELCA) and adjunctive balloon angioplasty for in-stent restenosis. MATERIALS AND METHOD: We included 29 in-stent restenotic lesions treated in 28 patients (18 men, 10 women, mean age 60+/-2 years) admitted to Samsung Medical Center between June 1997 and August 1998. Quantitative coronary angiography was performed and clinical characteristics, acute complications, 30-day and 8-month major cardiac adverse event rate was analyzed. RESULTS: Initial success rate was 97%. We stopped the ELCA procedure in one lesion located in the proximal left anterior descending artery due to bradycardia and hypotension. In the 28 lesions successfully treated with ELCA and adjunctive balloon angioplasty, the minimal luminal diameter increased from 0.7+/-0.1 mm before ELCA to 1.9+/-0.1 mm after ELCA and to 2.7+/-0.1 mm after adjunctive balloon angioplasty (p<.0001). The acute luminal gain after ELCA was 60%. The diameter stenosis decreased from 75+/-2% before ELCA to 36+/-2% after ELCA and to 15+/-2% after adjunctive balloon angioplasty (p<.0001). There was no in-hospital death, Q wave acute myocardial infarction (AMI), emergency coronary artery bypass graft (CABG), but non-Q AMI was noted in 1 case (3%). During the followed-up period of 8 months, there were 1 death (4%) due to congestive heart failure, 1 nonQ-AMI (4%) and 7 target lesion revascularization (26%) among the successfully treated 27 patients, but there was no CABG, Q-AMI. Combined event rate at the 8-month follow-up was 33% and target lesion revascularization rate at 8-month follow-up was 26%. CONCLUSION: The ELCA and adjunctive balloon angioplasty seems to be safe and effective for the treatment of in-stent restenosis. A prospective randomized trial comparing ELCA versus other ablative technique is required.