Coronary artery radiation therapy (CART) has become the standard of care for the treatment of coronary instent restenosis after repeat angioplasty. More than 5,000 patients have been enrolled into various clinical trials using 3 major systems. Based on the results of GAMMA I and START trials, both the Checkmate system using 192 Ir and the Betacath system using 90 Sr/Y have been approved for routine clinical use in the treatment of in-stent restenosis. The Galileo system using 32 P with data from INHIBIT trial is pending premarketing approval. With a better understanding and application of radiation oncology concepts to vascular brachytherapy, problems such as geographic miss and/or edge failure should be overcome. The complication of late thrombosis should also become less notable by eliminating restenting at the brachytherapy procedure and the prolonged use of antiplatelet therapy. Although there are other competing modalities in the very early phases of clinical trials, the future of CART appears bright. The durability of results, lack of any important complications, and confirmation of the efficacy in other sites will further consolidate the role of CART in preventing vascular restenosis.