BackgroundThe aim of this paper is to compare common features and variation in the work of research ethics committees (RECs) in Finland to three other countries – England, Canada, the United States of America (USA) – in the late 2000s.MethodsSeveral approaches and data sources were used, including semi- or unstructured interviews of experts, documents, previous reports, presentations in meetings and observations. A theoretical framework was created and data from various sources synthesized.ResultsIn Finland, RECs were regulated by a medical research law, whereas in the other countries many related laws and rules guided RECs; drug trials had specific additional rules. In England and the USA, there was a REC control body. In all countries, members were voluntary and included lay-persons, and payment arrangements varied. Patient protection was the main ethics criteria, but other criteria (research advancement, availability of results, payments, detailed fulfilment of legislation) varied. In all countries, RECs had been given administrative duties. Variations by country included the mandate, practical arrangements, handling of multi-site research, explicitness of proportionate handlings, judging scientific quality, time-limits for decisions, following of projects, role in institute protection, handling conflicts of interests, handling of projects without informed consent, and quality assurance research. The division of work between REC members and secretariats varied in checking of formalities. In England, quality assurance of REC work was thorough, fairly thorough in the USA, and not performed in Finland.ConclusionsThe work of RECs in the four countries varied notably. Various deficiencies in the system require action, for which international comparison can provide useful insights.Electronic supplementary materialThe online version of this article (doi:10.1186/s12961-016-0078-3) contains supplementary material, which is available to authorized users.