Background: Trial registration is an ethical, moral and scientific obligation. Mandatory trial registration was introduced by the International Committee of Medical Journal Editors (ICMJE) in September-2005, in an effort to promote transparency of trial design and reporting, and reduce potential biases. Objective: To evaluate the number of randomised controlled trials (RCTs) that have been registered and the proportion that declare this registration in related publications. Methods: We investigated a cohort of trial reports from the Cochrane Renal Group s specialised register. We included any kidney transplantation RCTs reported in peer-reviewed journals between October 2005 and December 2008. Registration status was established by searching the WHO international clinical trials registry platform, which links international clinical trial, registers. Registration declaration was established by examining study publications for trial registry identifiers. We assessed potential predictors of trial registration and of registration reporting using logistic regression. Results: 432 reports of 262 studies were included. 60 (24%) studies were registered. 30 (50%) registered studies declared their trial registration number within the study publication. Studies with larger sample sizes and those that were blinded were significantly more likely to be registered (Table1a). Studies that were registered were significantly more likely to declare this on publication if blinded but significantly less so if funded by a Pharmaceutical company (Table1b). Potential predictors of trial registration and registration declaration are reported in Tables 1. Conclusions: The majority of RCTs in kidney transplantation reported from 2005 onwards have not been prospectively registered, and even when registered often do not cite registration status when publishing study results. While these results may not be generalisable to other specialties, it does seem that there is a general failure of compliance with trial registration.