The antiproliferative effects of radiotherapy have been used clinically for over 100 years to treat several benign disorders. More recently, several experimental studies have convincingly demonstrated that the use of intracoronary radiotherapy results in marked modulation of the restenotic process. Currently, several systems are undergoing clinical evaluation. Radiotherapy with gamma radiation has been conclusively shown to have a major impact on the long-term prevention of restenosis following percutaneous intervention. Several systems using beta radiation, delivering a more localised form of radiotherapy, have also been used with very promising results in the short to mid-term. Whilst inhibition of restenosis at the target site is a consistent finding, both forms of radiotherapy can be complicated by recurrences at the edges and by late thrombotic occlusion. Both these limitations should be minimised by improved lesion coverage by the radiation source and by prolonged (6 months) anti-platelet therapy. Although there is clear convergence of evidence to suggest that many radiotherapy systems are highly effective in the short and mid-term, a prolonged follow-up period over several years will be necessary to make a definitive conclusion about their wide-scale clinical application.