BACKGROUND We are presenting an extension of a previously published trial on the efficacy and safety of a paclitaxel-coated balloon in coronary ISR in a larger patient population and after a complete follow-up of 2 years. METHODS Hundred eight patients were enrolled in two separately randomized, double-blind multicenter trials on efficacy and safety using an identical protocol. Patients were treated by the paclitaxel-coated (3 microg/mm(2) balloon surface; Paccocath) or an uncoated balloon. The main inclusion criteria were a diameter stenosis of >or=70% and <30 mm length with a vessel diameter of 2.5-3.5 mm. The primary endpoint was angiographic late lumen loss in-segment. Secondary endpoints included binary restenosis rate and major adverse cardiovascular events (MACE). RESULTS Quantitative coronary angiography revealed no differences in baseline parameters. After six months in-segment late lumen loss was 0.81 +/- 0.79 mm in the uncoated balloon group vs. 0.11 +/- 0.45 mm (P < 0.001) in the drug-coated balloon group resulting in a binary restenosis rate of 25/49 vs. 3/47 (P < 0.001). Until 12 months post procedure 20 patients in the uncoated balloon group compared to two patients in the coated balloon group required target lesion revascularization (P = 0.001). Between 12 and 24 only two MACE were recorded, a stroke in the uncoated and a target lesion revascularization in the coated balloon group. CONCLUSIONS Treatment of coronary ISR with paclitaxel-coated balloon catheters persistently reduces repeat restenosis up to 2 years. (ClinicalTrials.gov Identifier: NCT00106587, NCT00409981).