Randomised clinical trials are regarded as the highest level of evidence for informing clinical guidelines and clinical practice. The robustness of conduct and reporting of the results of randomised clinical trials is therefore of primary importance. To improve the transparency and quality of reporting of clinical trials, the International Committee of Medical Journal Editors (ICMJE) endorsed a policy on mandatory registration of clinical trials, which came into effect in July 20053. The trial registration recommendations outlined by the ICMJE state that a trial must be registered in a publicly accessible registry, before the enrolment of the first study participants, in order to be considered for publication. This policy is designed to reduce publication bias, prevent selective reporting of desirable or non-reporting of undesirable results, and reduce research waste by making the research community aware of what questions are already being addressed by active trials.