BACKGROUND AND OBJECTIVES: Intracoronary irradiation has emerged as a successful intervention for the treatment of restenosis. However, the radiation process is complex, difficult and hard to perform. On the contrary, intracoronary radiation therapy using a 188Re-DTPA-filled balloon system is simple and inexpensive. The short-term follow-up results of this system have been reported, but the long-term results remain to be elucidated. The object of this study is to evaluate the short and long-term follow-up results of intracoronary radiation using a 188ReDTPA-filled balloon system in restenotic lesions. SUBJECTS AND METHODS: Thirty-eight patients, with restenotic lesion after previous percutaneous coronary intervention, were selected from the SPARE trial (Seoul National University Post-Angioplasty RhEnium irradiation trial). There were 27 cases in the irradiation group, with 11 in the control group. Irradiation was performed in the restenotic lesions after successful interventions. The results of 6-month angiographic and 6-month and 3-year clinical follow-up data were compared between the two groups. RESULTS: A 6-month angiographic follow-up was performed in 33 patients (87%), 25 in the radiation group and 8 in control. Binary restenosis developed in 1 of 25 (4%) and 4 of 8 (50%) in the radiation and control groups, respectively (p=0.008). At the 6-month clinical follow-up, there were no significant differences in the event rates between the two groups. At the 3-year clinical follow-up, there was a significant difference in the target vessel revascularization: 2 of 27 (7.4%) and 5 of 11 (45.4%) in the radiation and control groups, respectively (p=0.017). There were no deaths or myocardial infarctions. CONCLUSION: Radiation therapy using a 188ReDTPA-filled balloon system is feasible, and may be effective in improving the long-term outcomes in restenotic lesions.