Objectives To assess the potential role of clinical trial (CT) registries and other resources available to research ethics committees (RECs) in the evaluation of complex CT protocols in low-income and middle-income countries.

Methodology Using a case study approach, the authors examined the decision-making process of a REC in Argentina and its efforts to use available resources to decide on a complex protocol. We also analysed the information in the USA and other CT registries and consulted 24 CT experts in seven countries.

Findings Information requested by the Argentinean REC from other national RECs and ethics’ experts was not useful to verify the adequacy of the REC's decision whether or not to approve the CT. The responses from the national regulatory agency and the sponsor were not helpful either. The identification of international resources that could assist was beyond the REC's capability. The information in the USA and other CT registries is limited, and at times misleading; and its accuracy is not verified by register keepers.

Discussion and conclusion RECs have limited access to experts and institutions that could assist them in their deliberations. Sponsors do not always answer RECs’ request for information to properly conduct the ethical and methodological assessment of CT protocols. The usefulness of the CT registries is curtailed by the lack of appropriate codes and by data errors. Information about reasons for rejection, withdrawal or suspension of the trial should be included in the registries. Establishing formal channels of communication among national and foreign RECs and with independent international reference centres could strengthen the ethical review of CT protocols.