Randomized controlled trials (RCTs) provide the highest level of evidence in clinical research and are the foundation of evidence-based medicine.1 However, ongoing challenges continue to face surgical trials. These include the small number of studies relative to the number of important questions, the fact that many studies fail to recruit, as well as the uncertain applicability of outcome data to real-world practice due to often stringent eligibility criteria.2 In addition, a major factor with limiting trial initiation is the cost of traditional RCTs, a significant component of which is associated with data collection. Clinical registries are databases that collect patient, treatment and outcome data in routine care, potentially supporting a large range of research and audit projects. An emerging clinical trial methodology, the registry-based randomized controlled trial (RRCT), has been introduced to reduce barriers to opening trials, particularly to reduce costs and to facilitate the enrolment of more real-world patients. This pragmatic study design utilizes registry databases to collect trial outcome data, with patients randomized between current standard-of-care treatment options.3, 4 Registry databases can also be used to identify trial candidates. With typically broad entry criteria RRCTs support high-quality outcome data being captured in the clinical registry, obtained from enrolled patients representative of the “real world” population. The capabilities of RRCTs in clinical research were initially demonstrated via two landmark cardiology studies, the SAFE-PCI for Women trial (Study of Access Site for Enhancement of Percutaneous Coronary Intervention for women) and the TASTE trial (Thrombus Aspiration during ST-Elevation myocardial infarction in Scandinavia).4, 5 These practice-changing studies utilized comprehensive national registries, were able to collect high-quality patient data on 9458 and 7244 patients, respectively, and were completed at a fraction of the cost of standard RCTs. In Australia, several RRCTs are recruiting patients from oncology registries. For example, the ALT-TRACC trial is a phase II RRCT using an Australian-based international metastatic colorectal cancer registry (TRACC) to compare alternating oxaliplatin and irinotecan-based chemotherapy versus the current standard of care of continuing one doublet till progression.6 Unfortunately, the utility of RRCTs in surgical research has yet to be explored in Australia. The benefits of an RRCT include, due to the more inclusive entry criteria, the ability to recruit more patients from culturally and linguistically diverse backgrounds, older patients and patients with co-morbidities. Fewer exclusion criteria can also mean studies of patients with rarer diseases, who traditionally are challenging to recruit to RCTs. Less costly studies that can be opened at centres with less trial support infrastructure also means more sites can be opened, a boon for recruitment. The registry component of RRCTs ensures that treatment and data that are routinely captured in institutional and administrative systems can be used to populate the registry. When much of the data is already being routinely captured into the registry for consecutive patients, irrespective of trial involvement, the need for additional extensive data collection or follow-up for trial patients is circumvented.7 Running an RRCT, therefore, becomes much more cost-effective. The linkage of existing registry infrastructure results in the reduction of study duration due to easier identification of patients, streamlined recruitment and completion of follow-up, and the added benefit of lower administrative demand.8 There are still limitations to the implementation of RRCTs. RRCTs still lack the high internal validity of traditional RCTs, and there are ethical issues to consider, including how individual patient consent is obtained.8 There must be equipoise about the use of the treatments being compared, and clinicians and patients must be interested in the research questions. High-quality adverse event data can be difficult to capture, and ideally hard endpoints, such as 30-day mortality or hospital length of stay, are used. Many institutions still lack a robust registry system. Therefore, to facilitate this, investment in registry expansion, integrating randomization software, installation of appropriate hardware, improving cloud capability, provision of maintenance, and training and support for clinicians and administrators will be required.7, 9 Furthermore, the collected data needs to be of high quality, which must be a continuing focus to ensure registry longevity and utility. The implementation of RRCTs into surgical practice could be challenging as, currently, this model has been focused on and validated in primary prevention and drug trials.9 However, there are no intrinsic reasons why surgically focused RRCTs should present unique challenges, particularly given the success of interventional registry trials such as TASTE and SAFE-PCI. Furthermore, developing Clinical Quality Registries (CQRs) and implementing an effective data linkage process between CQRs or similar registries with current electronic medical records (EMR) can also be useful. This can make RRCTs much more cost effective and efficient and could enable researchers to conduct dynamic analyses using real time data.7 Registry randomized controlled trials have enormous potential in future clinical research, including for surgical researchers. They allow for the inclusion of ‘all comers’ that would be considered fit for treatment in the real-world context to answer a ‘real world’ clinical question. More support in developing registry infrastructure, trial set-up and integration into surgeon workflow will help promote the development of this novel trial methodology. System process variability including ethics governance, patient randomization, data collection and trial reporting require standardization. Further consideration of the current consenting process appropriateness in RRCTs is essential. We believe RRCTs can provide a more cost-effective and robust study design for future prospective research in surgery. Open access publishing facilitated by The University of Melbourne, as part of the Wiley - The University of Melbourne agreement via the Council of Australian University Librarians. Yasser Arafat: Conceptualization; writing – original draft; writing – review and editing. Matthew Y. Wei: Writing – review and editing. Bill Karanatsios: Writing – review and editing. Shehara Mendis: Writing – review and editing. Peter Gibbs: Supervision; writing – review and editing. Justin M. C. Yeung: Conceptualization; supervision; writing – review and editing.