Background: Publication of complete trial results is important for clinicians, consumers and policy makers in order to make better-informed decisions about health care. The phenomenonwhereby studies that are not submitted or published based on the strength and direction of the trial results has been termed ‘publication bias.’ An important issue which has received less attention is adherence to the protocol. There is evidence to show discrepancies between what was originally planned in the protocol compared to the publication. Objectives: To assess protocol adherence of RCTS, by considering cohorts of clinical trials that have assessed any aspect of the reporting of RCTs compared to information stated in the protocol. Methods: Studies will be identified through electronic searches, known item searching and scanning reference lists. Any cohort study comparing protocols to publications of primary studies for any aspect of trial design or analysis will be included. Studies will not be excluded based on language of publication or a quality assessment. Data regarding: differences between protocol and publication, quality of the primary RCTs (however measured in the included cohort study) and the quality of the included cohort study, will be included according to pre-specified criteria. Potentially eligible studies may not compare all aspects of the protocol to the trial report. Therefore any study that evaluates any difference between protocol and publication will be included. If the cohorts are sufficiently similar and there is no evidence of substantial heterogeneity, results will be combined in a meta-analysis, otherwise a descriptive summary of the designs and outcomes of the included cohort studies will be provided. Results: There is a Department of Health deadline for completion in September. Therefore, results will be presented at the colloquium. Conclusions: Protocols should be adhered to and substantial changes to the protocol should be submitted to the ethics committee. Any differences between the protocol and final publication should be discussed in the trial report and justified.