Seeking ethics committee approval for research can be challenging even for relatively simple studies occurring in single settings. Complicating factors such as multicentre studies and/or contentious research issues can challenge review processes, and conducting such studies internationally adds a further layer of complexity. This paper draws on the experiences of the LINNAEUS Collaboration, an international group of primary care researchers, in obtaining ethics approval to conduct an international study investigating medical error in general practice in six countries. It describes the ethics review processes applied to exactly the same research protocol for a study run in Australia, Canada, England, the Netherlands, New Zealand, and the US. Wide variation in ethics review responses to the research proposal occurred, from no approval being deemed necessary to the study plan narrowly avoiding rejection. The authors' experiences demonstrated that ethics committees operate in their own historical and cultural context, which can lead to radically different subjective interpretations of commonly-held ethical principles, and raised further issues such as 'what is research?'. This first LINNAEUS study started when patient safety was a particularly sensitive subject. Although it is now a respectable area of inquiry, patient safety is still a topic that can excite emotions and prejudices. The LINNAEUS Collaboration now extends to more countries and continues to pursue an international research agenda, so reflection on the influences of history, social context, and structure of each country's ethical review processes is timely.