Registries in cardiovascular medicine ingeneral, and within interventional cardiology in particular, have gained moreattention in medical journals over thepast few years. By consecutive enrolment of complete patient populations, the methodology is a powerful tool for describing healthcare, including the complications and benefits of different therapies. However, it is very importantto be cautious in the interpretation ofthe comparison of outcomes betweendifferent treatment alternatives in obser-vational studies and always consider them non-definitive and hypothesis generating. In order to avoid selection bias, randomisation of patients may be included within a clinical registry, combining some of the most important features of a prospective randomised trial with the key strengths ofa large scale clinical registry. Thereby prospective use of quality registries could potentially revolutionise clinical trials by the fast inclusion of large patient numbers, focus on hard end points and complete follow-up, and at a fraction of the costs of today’s randomised controlled trials.