During the set-up phase of an international study of genetic influences on outcomes from sepsis, we aimed to characterise potential differences in ethics approval processes and outcomes in participating European countries. Between 2005 and 2007 of the FP6-funded international Genetics Of Sepsis and Septic Shock project, we asked national coordinators to complete a structured survey of research ethic committee approval structures and processes in their countries, and linked these data to outcomes. Survey findings were reconfirmed or modified in 2017. Eighteen (...) countries participated in the study, recruiting 2257 patients from 160 ICUs. National practices differed widely in terms of composition of RECs, procedures and duration of the ethics approval process. Eight countries used a single centralised process for approval, seven required approval by an ethics committee in each participating hospital, and three required both. Outcomes of the application process differed widely between countries because of differences in national legislation, and differed within countries because of interpretation of the ethics of conducting research in patients lacking capacity. The RECs in four countries had no lay representation. The median time from submission to final decision was 1.5 months; in nine approval was received within 1 month; six took over 6 months, and in one 24 months; had all countries been able to match the most efficient approvals processes, an additional 74 months of country or institution-level recruitment would have been available. In three countries, rejection of the application by some local RECs resulted in loss of centres; and one country rejected the application outright. The potential benefits of the single application portal offered by the European Clinical Trials Regulation will not be realised without harmonisation of research ethics committee practices as well as national legislation. (shrink)