Background: The rate of drug-eluting stent (DES) in-stent restenosis (ISR) exceeds 10% in complex subsets of patients and lesions. The optimal management of DES ISR remains undetermined. Vascular brachytherapy (VBT) is proven to be effective for the treatment of bare metal stent ISR but its outcome for DES ISR has not been established. Methods: Ninety-nine consecutive patients who presented with ISR following DES implantation in 122 lesions were subjected to conventional percutaneous coronary intervention with adjunct VBT using either beta radiation (Beta Rail in 74 patients [82.2%] and the Galileo system in 13 patients [14.4%]) or gamma radiation (Checkmate system in 3 patients [3.3%]). Patients were followed clinically for major adverse cardiac events (MACE) during 1-year follow-up. Results: A high proportion of patients in this cohort presented with complex ISR; 31.1% had recurrences of ISR to the same site, 55% had diffuse or proliferate pattern of restenosis, and 23 lesions (18.9%) were located in a saphenous vein graft. Procedural success and uneventful in-hospital course were documented in all patients post VBT. At 12 months' follow-up, the target lesion revascularization (TLR) rate was 11% and the overall MACE rate was 26%. Patients with multiple episodes of ISR to the same site had a TLR of 16% and MACE rate of 35.5%. Conclusions: VBT for the treatment of DES ISR was found to be effective and safe and should be considered for the treatment of DES ISR, in particular in complex patients with multiple recurrences.